"After Kasparov broke from the corrupt FIDE, none of the following FIDE titlists were legitimate, until Kasparov retired." ~JamieDelarosa
I'll agree with most of that. The best player in the world from 1985 to 2000 was Kasparov. But in 2000, Kasparov lost his title to Kramnik. When Kramnik unified the title with his match against Topalov in 2006, Kasparov was already retired. The unification match wasn't contingent on Kasparov's retirement though, which is what your comment implies.
Btw, even Anand, who was a FIDE World Champion, has said that his match-play title was more important than his earlier World Championship title. The current World Cup is very similar to the FIDE World Championship that was held from 1999-2004. Nobody in their right mind would declare the winner of such a crap shoot the world champion, especially when the best player in the world wasn't involved.
I think most or all of us agree with that. The FIDE champions can't really be considered true champions until Kramnik won the reunified title.