The problem is that it's just inherent in a community. It can, and probably will, happen here at some point and probably already has to some extent. People will naturally gravitate towards like minded "in-groups" and, given enough time, that will expand into its own echo chamber.
I think it might help to differentiate "I disagree" and "I don't like this" downvotes from "this thing is a waste of resources" or "I don't care what this person has to say, they are an asshole that I don't want to interact with" ones. Comment filtering should use the latter rather than the former.
Allowing controversial comments to still be a part of the conversation without a "this isn't popular!" target painted on them might avoid the echo chamber effect while still giving users a way to passively disagree.
It's not that, it's more that usually comments that are heavily downvoted get hidden and so see less real discussion, plus reddit starts rate-limiting you when you're heavily downvoted.
Lemmy seems to be better in that I might get downvoted, which is fine I don't give a fuck, but you don't get limited so you can still reply and have discussions.