This is one of the worst arguments EVER for being against cross server WZs. I mean it.... really, it is a fake or like an urban legend. Community comes from what happens in the world, you know, like WORLD PVP. Warzones, Minigames, Battlegrounds, WHATEVER you want to call them, do nothing but add a carrot for the masses.
The best PVP ALWAYS comes out of world pvp, never some minigame. And communities are born from the conflict or friendships that is forged from those world encounters.