I think it's because of an old Canadian law that states that "have not" provinces are not allowed to headquarter Canadian banks.
At least, this seemed to be the rationale in the past whenever anyone dared suggest a bank move out of Toronto.
Seriously though. Federal cultural institutions are moving out west (or at least, being considered). Simply unthinkable 20 years ago, yet it's happening. I no longer doubt that even more bizarre things could happen. Things are changing in this country and I suspect the next generation might wonder why we still talk jokingly/derisively about Toronto being the "centre of the universe".