HN isn't a bunch of disconnected communities that sometimes overlap due to algorithmic feeds. It's one community with one front-page.

There may be a single feed, but it’s definitely a bunch of “disconnected communities”. That’s why half the people think HN is pro-AI and the other half thinks it’s anti-AI. Everyone gets the same feed but interact with different content on that feed and come to completely different conclusions.

Those are different individual values, not different communities. All of the conversation is co-mingled in the same threads that everyone sees. Everyone is expected to follow HN rules. 1 person can be a part of multiple communities.

An example of different communities would be subreddits. Reddit as a whole connects all of the communities with a front page, but each community is isolated from one another unless you choose to look over or someone else chooses to look into your community. Cross-community conversation happens from the overlap of subreddits followed between individuals.

That’s a silly definition. In real life everyone has access to the same street (feed) with the same shops/restaurants/bars/etc (posts), but people choose which of this they go to and they each have their own vibe. They don’t typically cross pollinate. So there are different “communities” within a “community”. Surely you don’t read and interact with every post, only those you are interested in.