I am not judging, but I can say this: I have been on many, many Internet mailing lists (and also Usenet newsgroups) for 18+ years, and I have managed and/or moderated 10s of them, some with subscriptions running close to a 1000 (and one with more than that). Flame wars (and the reputation of the Internet that they create, as you note above) on many of these forums are noteworthy because of they are flame wars i.e., they are occasional (and on some lists, frequent) outbursts of irrational argument that most recognises as counter-productive. To the point where it was often reduced to a sport -- on rec.motorcycles, we had a KotF, the keeper of the flame! The sort of "hatred, paranioa" I see on left forums (in particular the blogistan) seems to be of a very different nature. Attempts to answer your question above (and I don't have an answer) might be on the wrong track if they follow the train of thought of treating the generic flamewar and left circle circular firing as one and the same.
--ravi