They actually keep track of each other and interact. When Herself spent too long offline, she got a phone call from someone wanting to make sure she was okay. That's a community. The ability to respond to posts on a web site does not make a community. Recognizable personalities does not make a community.
People make a community.
But just having a group of people does make a community. I've lived in quite a few different houses that really didn't deserve to be considered part of a community either. Now I live in a house where I know my neighbors, where they know me, and we keep track of each other non-intrusively. Now I live in a community. Which is why I know what isn't one.