I agree perception always changes. And yes winning creates a positive perception, but I think people have the ability to think Durant is amazing, a top 2 player in the league, that the warriors are one of the greatest teams of all time AND that Durant’s move was weak and was bad for competitive balance. You dont have to believe one and not the other. People are acting like any sort of criticism is unfounded because he is winning, that is simply not understanding where the criticism is coming from.
I think the properly applied by other champions argument is dumb. Again no one is arguing Durant’s greatness or the greatness of GSW. They are actually fully acknowledging both, which is why they think his decision to go there was weak. This is not a debate about winning but competition within sports. Webber, Barkley, etc. have all been competitors, and they all have valid opinions. Winners aren't the only ones with valid judgement.