My guess is that many of the people that will easily start with being pricks in a game usually use skill related arguments as their supporting banner, and will, even without provocation, tell someone else they just suck and should stfu or gtfo the server.
Those people, in my opinion, probably have inferiority complexes and find being better than someone (anyone) else in a videogame is the only way they can feel better about themselves, and that they won't stand for anyone threatening what they perceive as their position of superiority.
Personally I've been at the receiving end of many accusations of hacking on the CSS:RPGmod server that was (is?) hosted by SGS. I never paid any attention to it and even tried helping those that accused me to understand how and why it is that I'm able to consistently beat them or even groups of people at once without easily dying, but I'd essentially always be met with hostility regardless of how I tried to help anyone.
Similarly on normal CSS servers, people will often complain about their mouse being a pain or their computer being abnormally slow; this is a normal thing for people to do because it's something many people experience and they have no other way to vent their frustration. Unfortunately, that doesn't mean there won't be at least one guy that pipes up telling you you're just a noob and that you can't play, and that you should just stop being a whiny little bitch or get off the server if you can't deal with how much you suck.
Often, I have to wonder if these aren't the kinds of people that are so used to being accused of hacking and that may actually be hacking, that they perceive even the slightest negative comment in a game they're on, no matter how unrelated it is to them, to be a potential threat to their hacking safety.
But then, maybe that's just me.
