Minor point, but is "gatekeeping" seems like slightly the wrong term for this, since they they aren't (I don't think) trying to keep anyone out of the hobby. Maybe it's a kind of elitism, or maybe just a mix of enthusiasm for non-dnd games and resentment of dnd's market share that comes off as elitism.I’ve seen the anti-D&D gatekeeping push a lot of people away from the hobby at large, over the last ten years.
In any case, one very off-putting example of this, by all involved parties, was some indie designers went in on critical role for playing Monster Hearts "wrong." One said he felt bad for the creator of the game, who I think was actually pretty happy to have critical role streaming her game to all their fans. But then said fans piled on these individuals, as they do.
Critical Role DM Matt Mercer Asks Fans Not To 'Dogpile' On His Critics