First of all, welcome to the internet. I hate it as well. Worse grouping of people ever, eh?
Second of all, it may not be the usual "random hate". I'd imagine a pro baseball team would be upset if you tried batting by poking the ball instead of swinging or doing something else completly ridicious.
No, we're not playing pro baseball. I know. The point is most people want a good game. When newer players are feeding the enemy team, walking around with 100 hp, and other idiotic things, it maks it hard to compete, let alone win. After a bit, there's just no point in playing. You can't vs 3 by yourself, your team is useless and helping the enemy more than you, and you basically wait another hour or so doing nothing while you get yelled at for being an afker.
Anyone would be upset. The correct way to react would be to offer advice. Sure, they should of played single player to get the hang of the game first, but whatever. Too late now. I, for example, offer advice such as "Hey, there's a snipe reg and you have 300 hp silly TB! Go heal!"
Usually, people react somewhat like what you are saying. "Stop being elitist, stop telling me what to do, blabhagaekjgaekfbaekbfgkaefb!". This lumps them with the first group of people. Anyway, after they die from a snipe after reg snipes a creep 3 times by mistake, they say he's over powered and bitch or leave or just giggle and go back to feed him some more.
Point being, I think we should encourage teamwork rather than hitting ignore on other players. Because that's probably a sure way to lose. Of course, if you want to ignore another player in the first place, chances are you're not going to win in the face of a team that works together.