For what it's worth, I usually give at least a mouse's ass, pd.
"Discussion" is a broad term, and I think the nature of the discussion makes a difference. More fact-based discussion/ knowledge sharing is more finite. More community-based discussion (digressions et al) is more analagous to "real life" interactions, in that you get to know certain people and certain backstories, but the personality itself is what becomes interesting.
Definitely needs ongoing infusion of new people to keep it that way, though. Hubby and I were recently musing when we were hanging out with some people we didn't know well that it was nice to have a new audience -- we enjoy listening to each other's stories, but don't usually tell them to each other when it's just us. ("There was this one time in Paris..." "Oh, you mean the missed flight?" "Uh, yes.")