The universe had shifted from one hand to another since AO left it.
First, Amaterasu took control right after he ceased to be, and she didn't even touch the Overgod portfolio. Amaterasu had ruled with her own power and made the universe hers by the authority of her stars.
Then, after her came Cain Lisworth, who managed to defeat Amaterasu and took the Overgod's portfolio and ruled the universe for over five thousand years, only to slowly crumble to madness.
The role of the Overgod wasn't something a mere god could endure, even with the help and protection of the Overgod's portfolio and authority. That only made the fact that Amaterasu ruled the universe without the overgod portfolio for millions of years even more puzzling and harrowing.
