I find similar things in youtube comments, facebook threads etc. A facebook page or youtube video with, say, pro Israel message gets a mob of commenters shouting down anyone who speaks about the plight of Palestinians. Meanwhile a page or video about "occupation" will have a mob shouting down anyone who speaks about Israel's right to exist. Very few in the mob actually make point by point rebuttals or even actual sense.

The same can be seen in religious forums, atheists, etc. Try to post in a religious stackexchange - with the notable exception of judaism.stackexchange.com your post is likely to be censoredor heavily modified if it's too critical or raises inconvenient issues.

At least, sites like quora and stackexchange have rules that tend to promote a clean end result, with quality answers. On social sites like facebook, however, things usually devolve into over 90% "bad" argumentation as defined by paul graham.

I think there is some internet study that anger and outrage motivates people to respond more than good things.

On Twitter, where people shout into the void and most people in the mob don't have a reputation to carefully manage, you can attract even more angry crap.

On YouTube it's the same principle - comments are public so the angry confrontations with low wuality argumentation are more likely.

The design of the site makes a huge difference. Which is why libertarians are just wrong, there is no "free market", every game has rules. You hear that libertarians? I am waiting for you on this thread!! :-P