I think that it's the nature of the Internet in general, and Forums / Chat programs in specific, that these things sometimes get out of hand. In a Real Life (RL) conversation, some one talks, and it's a very linear process. You can't go back and 're-hear' what he said 12 times, there are other distractions / sounds / activities going on that work to 'mute' the message being delivered.
In a posting type environment, there are no distractions, you read the words, not hear them, and that has a significant impact on how much you absorb and retain. You go back and reread that thing the other person wrote again and again, each time building up a bit more anger, till you fire off one the other direction.
The fact that the entire conversation is there as a permanent record also means that it's very tough for someone psychologically to even allow their position to modify based on the other persons arguments, not to mention the almost impossibility of admitting "You know, you may have a point... I'm going to have to think about this for a while".
I won't even touch how non-verbal cues that govern our interactions are non-existent, or the anonymous factor that can play a role also.
I'm glad that this forum is really VERY VERY civilized compared to some I frequent.
Steve W.
ps.. If people weren't so attracted by the prospect of a good fight, Don King would have to seek legitimate employment.