It's flattering to oneself to be contrarian; Not only have you already considered what has been presented, you've also thought about it and have a counter-argument. You're cleverer than the author of the article; she still entertains that idea while you have long ago dismissed it.
Thought that's rarely the case. What usually happens is someone will read a clever article, get upset that they didn't come up with it and choose a narrow interpretation or a minor nitpick to attack the piece, thereby making themselves feel better.
This is very well articulated and at least partly rings true for me. However, after typing out a response of the nature you described, I hit the back button rather than submit.
Funny. I thought that was my thing. Typing out a disagreement comment, then read it and think: "How will this discussion end? Will any good conclusion come out of it, or will it be mere sword flailing?".
More often than not, I hit back instead of submit.
Maybe it is also a reaction to what is often remarked upon as the falling signal to noise ratio: if everyone may expect to be skewered, then fewer will be encouraged to post.
Thought that's rarely the case. What usually happens is someone will read a clever article, get upset that they didn't come up with it and choose a narrow interpretation or a minor nitpick to attack the piece, thereby making themselves feel better.