I've been discussing this on Mastodon too, but more focused on features and limitations related to federation rather than people being dumber in one place or the other. But I also want more open conversations, which is one of the things I believe ActivityPub helps with.
So instead of voting for Lemmy I'll go ahead and say I prefer Kbin since I've found it easier here to interact with posts from other fediverse platforms.
Just read carefully the rules of each group/magazine/community as everyone is free to tidy up their spaces as they wish, reasonably or not.