Here again we are faced with the common PvP griefer's refrain of "I'm not breaking any game rules". That's not the point. In real life, according to the "rules" (i.e. the physical laws of our universe), nothing is stopping me from walking up behind unsuspecting passers-by and bashing their brains out with a tire iron; but I don't, because we as humans have developed a society out of the framework of physical law which details CONSEQUENCES for such an action.
In the same way that God created the world (for the purposes of this metaphor, at least) but humans created society, the CoH/WoW/Eve/etc devs created the world, but players created the society. So if an 80 belf ret pally is griefing my little level 20 nub in Darkshire, it's "within the rules of the game", but it's unequivocally bullying. It's no longer a matter of skill; my little level 20 nub has exactly 0.00% chance of beating an 80. But like in real life, the WoW society has developed consequences; those same rules allow me to bring out my 80 rogue to slaughter and camp his ass til he logs whenever I see him from then on.
Under the faulty logic that anything the laws of the game world permit is socially acceptable, any bug or exploit is fair game. Counterstrike players remember the bug in cs_assault that let an unscrupulous player pop up through the ceiling of the warehouse onto the roof. It's permitted under the laws of the CS universe, but any server admin worth his salt would perma-ban the little s**t.
The point is that the rules that the player society develops are just as important (if not more) than the physical rules of the game world itself. And if you flagrantly, gleefully, maliciously disregard them, like in real life, there are consequences.