I enjoy watching Youtube, for instance, but I can't stand the comments there. 99% of them [purely invented statistic] are from douchebags trying to insult other douchebags. I see the same thing happen on numerous other forums.
RoR and a few other sites do try to keep the discussion on a civil, intellectual level, and they (for the most part) avoid flame wars, which makes those discussions much more fun and enlightening to participate in or simply to read. The typical internet arguer should use these sites as a model to improve his discourse. But then, some people do just get off on being horrible. Go figure.
[Yes, I realize the irony of spewing invective about random hypothetical people for their doing a similar thing in a more direct manner. I enjoy that little twist, in fact. Am I a complete hypocrite, then? And does my knowledge of my own hypocrisy (and my enjoyment of its irony) excuse it or compound its fault? Or am I just an outright bad person? I'll stop now. I'm having way too much fun with this circle of thought.]