Hi, I don't usually post here anymore, but I come back once in a while to peek, and I think this discussion is very interesting.
I'll start by answering the question: The Mine 5 and Secret 3 were BAD for the show itself. For the racers involved, it was good because it got them into the F5 and F3 respectively. I call this good strategy but bad TV.
However, not all alliances are bad TV. The short-term alliance between Leo & Alana and Kaylynn & Haley was great to watch, imho. We see Leo & Alana helping Kaylynn & Haley in Leg 2, then Kaylynn & Haley returned the favor on Leg 3 involving the U-turn. I think that was nice.
Let me detail all alliance impacts per leg:
Leg 2: Short-term alliance by Leo & Alana with Kaylynn & Haley. It wasn't that bad yet. I think Will & James saw this as a turning point when they struggled with the horn in Colombia. It was a reaction for them to solidify an alliance to get help from other top-running teams, and in exchange, they're willing to help other teams as well to make it far into the race.
Leg 3: The Mine 5 is put into action. The teams within the alliance helped each other locate where to buy the items within the market. The purpose of the Mine 5 was to go into the F5, and not sabotage the teams not in it, thus the U-turn by Will & James was part of the reaction in struggling with the horn in Colombia, and Hung & Chee didn't burn the board to not give Leo & Alana a chance. Both sides of the detour didn't need teams to help one another, so I thought the task was designed really well while also including the Amazon lifestyle into it.
Leg 4: The switchbacks were also well-designed in the sense that teams can't help one another. Maybe the strategy with the watermelons is share-able? Nobody did anyway, but there was some subtle helping in the cello roadblock. It was guiding someone else and giving them tips rather than outright answers, so it wasn't that bad yet.
Leg 5: The first roadblock was great in the sense that every racer doing the roadblock can't use the same person from the same artwork. While they can help someone else find another answer for... let's say Aparna, they risk themselves taking more time helping out another team. The second roadblock was very individual. No problem with that either. The pie task only took out the suspense for Will & James and Hung & Chee, and from a production standpoint, it is disappointing, but only 2 teams got away with it for allies helping them. It didn't help either team advance anyway, but it did prevent them more from dropping it and having to do it all over.
Leg 6: Ah, the turning point for production. There's a difference between giving tips or guiding fellow racers with the task, and outright sharing answers. Like a lot of people thought, the task had potential to not be linear, but it was ruined by so much answer-sharing. I read exit interviews of Leo & Alana and listened to Justin's (TAR27) recap also with Leo & Alana as guests, and it's easy to tell that production didn't like the answer-sharing that they had to reprint the clues to prevent teams from sharing answers on the Kazakh detour. This was a NEL, so the answer-sharing only made it bad to watch, but it wouldn't affect who gets eliminated.
Leg 7: As mentioned on the paragraph above, production didn't want teams to share answers for the Kazakh detour. Among the Mine 5, only Hung & Chee picked that side of the detour anyway, so it doesn't really matter, but at least production made the extra measure to stop teams from sharing answers to advance together. They can easily give away answers, and that looks really bad on TV compared to just guiding allies. The alliance made more of an impact with peer pressuring Kaylynn & Haley to yield Leo & Alana. Without the Mine 5, Kaylynn & Haley wouldn't have yielded Leo & Alana, but it didn't really matter in the end, because Leo & Alana's mistake took themselves out.
Leg 8: After it was mentioned in the previous clue that this is the last leg to use the yields, Will & James and Riley & Maddison took this opportunity to yield the only team not in the Mine 5. Again, it didn't affect Kaylynn & Haley's cause of elimination, but without the Mine 5, there might've been a good opportunity to put someone like Hung & Chee behind, as I heard from Justin's recap for the episode. There was potential for answer-sharing at the number trap detour, but I'm glad nobody did, maybe because it was also stated in the clue that it's not allowed(?) or maybe because it was just too easy with the cheat sheet. The first roadblock prevented teams from sharing answers, but the second roadblock gave teams the opportunity to guide one another. This allowed James to get the roadblock done in his first try, and it also allowed Hung to pass Aparna in finishing the task. It was more of guiding allies rather than outright giving them answers, which isn't possible for the task, so it didn't seem as bad. From a viewer's perspective though, we see the Secret Final 3 alliance forming.
Leg 9: The Mine 5 made it to the F5! The Mine 5 may have swayed the yields to their favor, but none of the eliminations of the non-Mine 5 teams were directly caused by the Mine 5. The Mine 5 didn't really do any harm on the non-Mine 5 teams as their purpose was just to help one another get to the F5. As others have mentioned, (1) Jerry & Frank screwed themselves by leaving their bags behind, (2) Mich & Vic struggled with navigation themselves, (3) Leo & Alana did poorly at the detour, and (4) Kaylynn & Haley's awful cab luck put them behind. Even though Eswar & Aparna benefited the least from the alliance, it protected them from getting yielded in the previous leg. Now that the Mine 5 fulfilled its purpose, it's gone, and Gary & DeAngelo U-turned Eswar & Aparna fair and square. However, it felt so sour to me though that the actual sabotaging begins here, in the form of a defensive play too. I get why Riley & Maddison used it. It was to prevent Will & James or Hung & Chee from getting U-turned by Eswar & Aparna. Riley & Maddison didn't need to burn the board, but because of the Secret 3 alliance, they did and they screwed Eswar & Aparna in the process. I thought Eswar & Aparna were robbed for this reason, as burning the board didn't give them a chance to catch up. There was no answer to share in the tasks this leg, but the defensive U-turn play by Riley & Maddison was a nail to the coffin for Eswar & Aparna.
Leg 10: Teams could've helped each other at the kalesa task, but I'm glad they didn't. The music and memory task was so challenging though. After watching the episode twice, the France and Paraguay musics were so hard to match to their rock versions. On one hand, that made the task really tough to finish. On the other hand, teams didn't really read their clues until they got stuck, so guessing was possible if they at least read their clues. If the producers had been more strict, maybe they would've mentioned in the clue that sharing answers isn't allowed. It's one thing for Hung & Chee and Will & James to tell Riley & Maddison about what's on the clue. It's another thing to be directly given the answers from Riley & Maddison. Obviously, telling another team what's on the clue isn't the smartest move on the penultimate leg, but the teams were able to get past this loophole since it wasn't mentioned on the clue. I guess production just wasn't expecting teams to share answers on the penultimate leg, so they weren't as strict about it. Well, maybe it would've been better for them to just not take chances next time.
Addendum: Forgot to add that this F3 alliance screwed Gary & DeAngelo brutally. While Eswar & Aparna didn't know about the Secret 3 causing them to not be able to use the 2nd U-turn slot last leg, Gary & DeAngelo saw with their own eyes the F3 alliance helping each other on the music memory challenge, icing out Gary & DeAngelo and causing them to be frustrated enough to just take the penalty, even though they were so close to the correct answers twice. They were the first to ask for help, and while I don't think they deserved help because this is the penultimate leg, the other teams didn't deserve it too and yet they got help for being in the F3 alliance, which made them advance themselves to the finale.
Because of the strong alliances this season, I think production will be more strict about answer-sharing in future seasons. If they're even more strict about it, they'll even prevent teams from talking to other teams. That way, they can't even tell another team to read the clue or guide them in tasks. But then, we'd miss the opportunity for good short-term alliances like that of Leo & Alana and Kaylynn & Haley. Perhaps having teams talk to one another should be prevented more towards the end. Answer sharing should be strictly prohibited in the future, although I think production has learned enough from all the answer sharing this season.
This season was themed a bit on back to basics, and I thought this was a missed opportunity for an intersection. I know why it hasn't returned: It's not that good, and in all instances of its appearance since TAR10, all the intersected tasks could've been done by one team. The intersection would've been interesting to see on the mega leg though. That could've screwed Hung & Chee like how the potential lack of an alliance could've screwed them too.
Another twist that could've prevented the alliance from all moving forward together? The infamous head-to-head. Imagine a team not in the alliance fragmenting it for winning the last head-to-head. I know it's generally hated, but I thought that was a good way to mix things up with the alliance.
But really, I think production just wasn't as strict at times when it comes to answer sharing. I guess they didn't expect it when it first happened with the sauerkraut in Berlin, so they adjusted and reprinted future clues, such as the one in Kazakhstan. Although, they should've learned from Berlin not to underestimate the allied teams for the answer sharing on the penultimate leg. I think production will be more careful and strict about this next time. By the way, with the amount of times teams did not read their clues throughout the race, we could've had so much potential for 30-minute penalties, for breaking the rules on the clues if those stated that sharing answers are not allowed.
Throughout the history of the race, there were teams helping one another that were fine to watch, and there were also those that ruined the task, the episode, or the season altogether. As much as I think the alliances were very effective strategic moves this season, they were so hard to watch at times. I just fear that future TAR teams will follow this strategy for its effectiveness, so I hope production won't miss these loopholes next time.
P.S. Did not proofread my thoughts.