John Hardly, I agree with most of what you've said. Another difference in the pub analogy is you can only be involved in one conversation at a time. (Well, exceptionally skilled individuals could probably be in 2 or 3 if they're going on in close proximity.)

It's interesting to note that at least in the political debates, people have to read what another person has written in order to disagree with them. Folks in the music threads often seem to post their own opinion/information and aren't interested in a discussion. Therefore, you get the one-liners such as "it's at my web page" or "it's in the DT" or "it was recorded by ____." I enjoy it when someone can come up stories about the music, but it doesn't happen very often.