definitely agree, though the way that lemmy isn't overseen by a single entity would likely mitigate some of the negative effects in my opinion. but there's definitely a sweet spot between inactive and dead communities and ones which are too active, in a way i tend to not be a fan of (thinking of mainstream subs like r/funny and r/askreddit's quality drop). in any case though, if an instance you're in gets too mainstream for your liking, you can just hop over to a new, smaller instance/community and join local groups they have there for similar interests ¯\(ツ)/¯