[lolinder]

I'm talking about interpersonal relationships, not tech. The phpBB model allowed for communities to be informally related by virtue of having overlapping members, without any need to have any technical feature that formalized those relationships.

In real life I can be a part of a bowling club and a church, and I don't need the club to know anything about the church. They're distinct entities related only by the fact that I am part of each of them.

This confusion is kind of what I'm getting at: modern "social media" and "social networks" have coopted the vocabulary of real human relationships to the point where people assume these words have technical meanings.