I suspect that for reddit specifically, homogenous opinion and lack of meaningful discourse has more to do with the voting/karma system and its inability to sca

I suspect that for reddit specifically, homogenous opinion and lack of meaningful discourse has more to do with the voting/karma system and its inability to scale well. Nuance gets crowded out because posts and comments presenting polarized opinions are much more likely to get acted on by readers than their more nuanced counterparts are. Posting and voting becomes more about the dopamine hit from the gained karma and sense of being correct than it is about discussion. This is why while it still isn't perfect, one can often see higher quality discussions in smaller niche subreddits where there's no critical mass to push dominant opinions. In those communities, posting extreme comments just makes one look like an attention seeking troll. So in my view, moderation or lack thereof is almost orthogonal to an online community's propensity for quality discourse. That seems more related to the designs of and incentives given by the software these communities run on.