RE: the question: ":Why do forum interactions become contentious". . .

I get the topics email every day and I check in on this forum but I don't spend much time here. There seems to be a high level of dysfunctional interaction.

I have had a much better experience with the audio forums on Facebook. They are much more tightly moderated and a**holes are removed pretty quickly. I also like the structure better that allows you to efficiently respond to individual posts in a thread. The overall level of ego also seems to be less. People generally want to share information and help each other.

I used to have a recording studio and there were some recording forums that were as bad as Audiogon. Gearslutz was the best example. You could always depend on a few jerks mucking up any good discussion.

Audiogon is worth a quick scan every day and there are a few threads like Thiel Owners have been extremely valuable and constructive. I paw through the trash to find the occasional diamond and try not to waste too much time in the process. 

As I recently posted in the cable debate thread,

"The conflict occurs when people need others to share their same beliefs"

Disagreements (about audio stuff) are often interesting and particularly when folks offer well thought-out arguments or personal observations to support their positions.  These forums would be boring without opposing viewpoints.  Having confidence in one's beliefs is fine, just keep the discussion on topic and tolerate those who disagree.   The consequence of not keeping disparaging remarks and personal attacks in check will be less participation on this site by potential new members and by others who do not want to put up with the antagonism.  Audiogon can decide what they want to tolerate, and then live with the result.

For what it’s worth, I participate and contribute to more than a few audio forums. The only forum that tolerates contentious and confrontational exchanges with regularity is this one. 
From what I have observed, confrontational  exchanges tend to be a feature, not an aberration, on this site. That is unfortunate, because I enjoy and appreciate much of the non-confrontational input I’ve received here.

Personally, I believe that the moderators and sponsors of this site intentionally, if passively, promote no-holds-barred discussion to differentiate this forum from others. 

Lack of self-confidence
-or-
the inability of some people to see that not everyone thinks, has the same perceptions, or has the same values as they do

This is supposedly a fun activity that we are discussing. And some people are insecure enough to want to impose RULES on how others SHOULD enjoy audio equipment?