For years the 'gatekeeping' was reversed for D&D (gaming in general), I am a cool kid so I am not going to be playing an a game with nerds and geeks so they were doing the gatekeeping from the otherside. Now the resentment from the players (sub consciously or otherwise) is when that cool kid (or someone they see as that 'cool kid') now comes along and wants to play - but without acknowledging that the game was good/cool all the time, that really it is only cool now because they want to play.
I am not saying this is everyone and certainly would not point the finger at anyone on Enworld(well maybe one) - but it is how some people think - the example of liking a band before it was big, often illustrates this point, people just want to be acknowledged for being 'right' all along.