I belive more people would show up for discussion if it were as you stated.
I wonder if thats what PH thinks when he posts this general statement to the begining of his threads. "Everybody be nice."
There's something else to consider about flame wars, and that is the less polite they are the more hits they get. This is due to the inflammatory nature of the discussion. Sure, it keeps some people away though. The flip side to this is that over-moderated threads are boring, and get less hits. Moderators have to walk a fine line between stifling discussion and keeping trolls in check.