My Little Pony XXXI: The Great and Powerful XXXie!

[Athaniar]

Well, given that she controls the sun, holds near-deific power, has ruled for a millennia, and before that defeated both Discord (with Luna) and Nightmare Moon, I'd say it's not all that unreasonable for her to be treated like that (not to mention she is also a kind and benevolent ruler, Tyrant Celestia not being remotely canon). If she wants to be treated like that, though, that's another matter.