Not that user but I don't think this is as difficult as you're making it out to be?

On Reddit, Instagram, Tiktok et al I can create a community on that platform. I can get find other people into Booktok, I can join the Rowing subreddit, I can get into Knittinggram or whatever. Posters expect roughly their micro-community to see their posts, users expect to see their micro-community's posts.

On hacker news I see the same community everyone else does. If HN was a vBulletin forum with threads posted for links it would function almost 1:1 the same, I guess all you'd need to change is a modification for making threads bump on vote behaviour instead of latest-post.