That's not necessarily true. There's both approaches at work here, one is the "themed community" one, and the other is the "universal citizen" one. That user/forum migration has not been implemented from the beginning (but it will hopefully asap), speaks rather more about the mindset of the developers. I myself would find it an absolute no-go if i would be participating in the technical desigh of a social server network, if servers were to own users and communities. That would lead to the exact same problems as corporate sites pose -- they are governed by people with specific mindsets, and that is to be avoided.