Whenever I'm reading about PvP, that quote always springs to mind. People who have played MMORPG's with more "hardcore" PvP systems have mentioned that the amount of random ganking you see in WoW just doesn't seem to occur on the same scale elsewhere. WoW's PvP is pretty consequence-free. Corpse runs are annoying, sure, and being camped is nobody's idea of fun. But you don't take durability or experience loss after a PvP death, and you don't lose money or items to the attacker. Nor does the attacker gain anything from killing you (unless it's honor if you weren't a gray target).
However, practices like these are pretty common in other games, to the extent that harsh penalties as a result of player death seriously alter gameplay. When you lose a ton of gold, XP, or hard-won items after a death, the risk-to-reward ratio is entirely different. Would-be attackers are also forced to ask themselves whether it's worth it to jump someone when the same gold/item loss will occur to them later once the gankee gets his revenge. There are even games where guilds that do nothing but avenge ganking deaths are common (and it may actually have been Diablo that first popularized this). You know you're not in Kansas anymore when you read old Ultima Online PvP guides that advise you to not to acquire a bad reputation because no one will help you if you get attacked, or reading recent EVE Online discussions about suicide gankers being able to manage 20 kills a week.
This is all rather unscientific of course -- it's the sort of thing I'd love to see numbers on, if I could -- but whenever I read any of the constant forum threads asking for PvP to become more hardcore, I'm pretty sure that what they want would actually result in less world PvP, rather than more.