Single community mode.
So with federation, each server being able to host an arbitrary number of communities can be a bit much. It makes sense for a site like reddit where it’s just one site. But for a network of sites, hosting multiple communities is really a niche thing, but people do it because why not? The feature is there. But most people spin up a server for a single community and the communities on that server become dead, save for a couple of bigger sites. Having and making known the ability for an admin to spin up a Lemmy instance that’s just one community makes a lot of sense. The server I’m currently using for example is for a diaspora from a single subreddit. Sites like that only really need a single community on them.
That your local feed is one community, that users can’t create any communities, that the landing page for the server is like HN or some other single community link aggregator site.