Yep, this is something I noticed as well. Reddit calls its subreddits communities, but most communities are not about the people but about the content. As you can only have nuanced conversation when you repeatedly run into the same people, the only subreddits able to withstand conversation are niche or heavily moderated like AskHistorians.

What this means is that if you want good conversation on Keyboards, it better be about mechanical. Good conversation on coffee or want a new pair of headphones? Better be into audiophile equipment. There's no room for generalists who just want good enough. Overnight WallStreetBets went from an interesting community of people willing to gamble far more than I to a pile of garbage.

I'm beginning to think that Dunbar's number and the associated tribal splits are something that we should factor into our community building, and not try to work around through metrics and algorithms.

So HN does this aspect correct, by grouping by interest of a certain type of person, but even on HN as more people show up and post the same problems will become evident.