I know it's mostly the fault of the matchmaker throwing in low rank players and not the players themselves, but I really hate people who win on their flank (or don't encounter enemies there) and then proceed to go camp there and are oblivious to the fact that their teammates are obviously (about to be) getting overrun elsewhere by an abundance of enemy players.
I wouldn't mind if they were at least GOOD at camping. But no, they camp a point (lets say the munitions area on Steppes) and think that throwing up sandbags, barbed wire and maxims will make that point invincible through to the late game.
Cue map pinging once a light tank simply rolls through the whole lot because they didn't bother to build AT.