I bet WoW also has rules governing pvp (active or passive) as do other pvp games (heck, even fps shooters have them sometimes). I seriously doubt any system that rewards only the strong has any longterm surviveability when it comes to population.
AoC might have tried some rules, but they are contraproductive (like the guards, the way kills are calculated, the way there are no consequences of actions) and they did not protect the weak, but in case of guards even helped the strong. They were mostly onesided patchwork attempts, but nothing compared to a self-regulating system.
This has nothing to do with a harsh and brutal world, it is just bad design. Conans harsh and brutal world had a consequence system too.