> First, the lack of a real threaded comment system.

> Second, the lack of a dislike/downvote, particularly an anonymous one.

I don't know. I agree that Facebook's commenting mechanism is ill-suited to deep discussion, but isn't the mechanism you're describing more-or-less exactly what exists on Reddit? And people are certainly able to self-segregate into bubbles on Reddit.

And for that matter, at least anecdotally I'd say that most of the political "discussion" that occurs on Reddit is low-quality, in that it tends to devolve into users shouting "fascist" or "cuck" at each other. (Some subreddits are better than others, admittedly.)

I suppose that Reddit users typically don't know each other in meatspace, though, and that Facebook is (mostly) different in that regard. Maybe that would make a difference. I don't know.