Why even have individual servers?

Q u o t e:
Now that Battlegrounds are cross-realm and arenas are cross realm, and soon even instances will be cross-realm. What is the point of even having individual servers, when you play the game with people you can't even send tells to or group with. They might as well all be bots, and WoW should be referred to as a single player rpg game. Unless u wanna make it for it with World and not instanced content, I think we're in trouble.

There are still so many aspects of game play specific to individual realms. Even with the new cross-realm Dungeon Finder being added in patch 3.3, players are still allotted the means to group only with players from their own realms. This is also required of the Arena system and possible with Battlegrounds, though you can't choose from which realm(s) your opponents originate.

This post seems so hyperbolic I'm unable to distinguish a real point.