More like a building where several strangers each pay for a flat, and people are free to come and go to different flats as they please.

I also think there would be a couple of distinct groups sticking to their own flats, and none of the others in the building wanting to visit them. These flats are known as “Defederated”. Now and then a newcomer will stumble through the door, have a look around, and decide to never open that particular door again.

Note that I’m not mentioning any particular instances, so if you feel offended by this, that’s probably on you.