Is there a difference between publicly announcing when and where the starting line will take place?
Is there a difference between talking about the 11 teams flying to Iceland before they have landed?
I'm sure someone can give a more definitive answer, but allow me to put in my two cents.
1) This season's starting line was publicly announced by CBS, so there was no question about anybody spoiling the start. RFF has, in fact, discovered some of the previous starting lines (through some excellent detective work) but does not publicly disclose this information until the racers have started racing (or, in at least one case, slightly before, when the racers are at the starting line).
2) This information was also disclosed through multiple sources this season, mostly because of the public start. Many people had a chance to learn the first destination from the racers themselves. I believe RFF mostly wants to protect the finish line and the final US destination, but again usually only discloses destinations when the racers are safely on their way.