This game's servers were not built in a way to handle super servers/ mega servers a la ESO. Assuming that you could even connect to the lobby alone, there would be massive queues. On top of that, there would be a great deal of disconnects as the servers try to handle the strain. Pretty much, it would be like the early days of 2.0 launch but far more exasperated.

Plus, try to imagine sitting in, say, Mor Dhona and listening to all the Ring of Thorns spam by Dragoons.