Perhaps. There's also the fact that people are communicating via typed messages, which are signal-deficient. People may be using a language which is not their first language.
People do not follow Postel's Law: "be conservative in what you send, liberal in what you accept" - saving that flaming response to draft and sending a few hours later would help.
Some online communities have been entirely too content with flaming and have done little to stop it.
And, I say this gently, some people just don't have the social communication skills they need.
Sorry to hear about painful typing - that sucks.
"None of us can claim a total lack of crazy or total lack of asshole" really hit the nail on the head.
And I'll remember "If you stop communicating, you're robbing yourself of a chance to practice." for the rest of my life.
Technical discussions can often be contentious, but often, they are contentious for the "right" reason, people care. When people actually care about building the "best" possible code, emotions run high, even though such unrestrained enthusiasm has substantial drawbacks. As you already know far too well, many thrive on the competition and conflict as much as they thrive on getting things right.
As Peter wonderfully points out, none of us can claim "A total lack of crazy," or for that matter, "A total lack of asshole." On top of these all too human failings, we also have our moments when we just get it all wrong. It happens. Roll with it. Let it go, but learn from it.
Good communication takes practice. Ask grellas sometime about the effort he put into learning to write well. It shows. He wasn't born the skill he has. He learned it. If you stop communicating, you're robbing yourself of a chance to practice.
As for me, I rarely post on HN due to my health not being very good. I deal with chronic pain, and often it hurts too much to type. As you might imagine, when I'm hurting a lot, I can often be less than pleasant company, and it's best for everyone for me to just remain silent. For me, typing comes at a cost. It means I'll be more sore by the end of the day. The cost has taught me something important; the things I say should make a difference, but often, my opinions don't really matter.
Treebeard: "You must understand, young Hobbit, it takes a long time to say anything in Old Entish. And we never say anything unless it is worth taking a long time to say." -- J.R.R. Tolkien