I haven't had a chance to finish the article yet, but I'd like to point out that WoW is far from free of griefing. Here are a few examples:
a) Alliance newbie is in the starter area, killing trolls. They go to kill one troll, only for that troll to turn around and slaughter them. Little did they realize it was a level 70 player from the Horde, dressed up just like the other mobs. They also don't realize that they have now been PvP flagged for 5 minutes, which means the second they respawn, the griefer will be waiting to take them under again. The PvP flag was put in place to prevent newbies unwittingly being entered into PvP combat, but the mechanics of it leave them quite vulnerable to provocation and scams like this.
b) You're a hunter trying to tame a rare creature. Of course, so are many other players of both factions. You get there first and begin taming. Another player (of either faction) is jealous for missing the opportunity and promptly slaughters the animal you are currently taming. Since what they did was just a normal part of the game (kill neutral monster), you have no recourse against them, even through the GMs.
c) You are grinding your way through enemies, trying to gain experience. Everytime you go to kill something, the griefer finishes it off. Since you got the first hit, it is "tagged" so that only you get experience, but since the experience you receive is proportional to the damage you have done and the griefer has killed it before you had a chance to do much damage, your experience is considerably reduced. Combine with a limited respawn rate and your experience rate is greatly reduced.
There are many ways to grief in WoW, many of them simple and within the rules of the game. Even in a game largely focused around PvE, any player interactions (even through the external environment) can be used for griefing.
I think there are some simple solutions to this. If we accept that players can always interact in some way conducive to griefing, then we need to give players the opportunity to defend themselves. Direct intervention from responsive GMs is a possibility, but it doesn't scale well and it's a constantly uphill battle. Instead, why not embrace the the fact that PvP is possible and allow them to fight back. Remove the "PvP doesn't exist here" shackles that imply safety and prevent retaliation and instead make it a free-for-all. It assumes that the principle of mutually-assured destruction applies, but it's been seen to work well in games like EVE Online and Warhammer Online. When we are all equal in ability, we all have to fear for our own safety, so we avoid provoking others.
The major downside to this is that, unchecked, equality can always be overcome. Larger groups of people, higher levels, better equipment, or even just skill, can result in a power discrepancy, in which case those with more power can grief without fear of retribution. This isn't an easy problem to solve; if you figure out a way, tell it to our legal system, who constantly struggles with the problem of policing the police.