"He does it toooooo so that means I'm not bad when I do it!" "He does this other thing that is way worse so that makes my bad thing a good thing!" is logic used by many for all sorts of things in game and in real life. Not just freeps towards creeps.
"The quest for excellence is a mark of maturity; the quest for power is childish"
Same exact reason creeps use freeps do it as an example.
People are typically only frustrated with behaviour that negatively affects themselves.
If you're playing freepside the vast majority of actions that frustrate you will be on your opponents side, creeps. Although there are often HUGE issues with our own side's behaviour as well.
I try to add the caveat to as many of my posts as possible that when I say "creeps" I really mean players because in all but a few situations players are players and the behaviours are easily witnessed on BOTH sides. A few class specific mechanics and the existance of maps aside.
That's the best rationale I can provide.
Second Marshal Luc Brandenbuck ~Battlemaster~
Stalker's Enemy*Reaver's Enemy*Blackarrow's Enemy*Warleader-Foe*Weaver's Enemy*Defiler-Foe Champion:'The only thing our opponents can do that we care about is die.'-Graalx2