I'd have to say that, as far as MMOs go, WoW is the exceptional outlier. And as for Blizzard, WoW's staff alone is massive. I'm willing to wager that it's several times larger than the staff that works on XIV and XI combined.

I don't know how financially well off SE is to consider adding another MMO developing staff. Right now, I'm leaning on that while they are doing fairly well right now, they're in no state to do such a thing.