I think what it really comes down to is a few people poisoning the well. Everyone has their preferences but you always have a few who are combative about it, which only breeds suspicion and defensiveness in others. I've seen one or two people enter a thread and turn it into a divisive flame-war almost instantly, when it was proceeding in a civil manner before. It just turns into a war of escalation and you have people writing things which cannot be unwritten.
A website I used to go to previously had this really, really awful fanboy. Everyone knew he was full of carp. Most of the people on his "side" generally ignored him. However, he could usually get a rise out of someone in the other camp, who would hurl back insults toward his console of choice, which would force others to rally to his cause. It was a quagmire that got worse and worse.
That's the curse of fanboyism, the way it draws people on the edges into the battle, like a riptide or a black hole.












