I've noticed something a little different in the past 10 years. I have had two 5E games wrap up one way or another. Probably about half the players are first time RPG players, the other half are long time D&D returners. Both groups eagerly jumped at the chance to try a new genre/system. In past, a lot of the players I knew and gamed with didnt want to learn a new system. I blame some of that on D&D popularity, but I think the bigger culprit was how heavy a lot of systems were a few decades ago. Thats a lot of homework when you have barely mastered the beast that is D&D.
I can't speak for anyone else but most of the time I simply don't have the time or desire to learn new systems. I don't get to play any game as often as I'd like and I only have so much head space for rules. If I want a change of pace there are hundreds of cool board games out there.
In addition, the ruleset for an RPG matters ... but not as much as the stories we tell. No matter what RPG I play, I'm still going to be playing make believe with some rules constraints.