Even though empowerment is now optional mechanically, IC a priest's powers are still coming from the gods, whether he is empowered or not.
IC, the guilds didn't suddenly come up with a way to access sups without calling upon a god. It's just that gods are more willing to lend some (lesser) power to a priest trained by the guild but not formally devoted to a specific deity. Obviously it means they can withdraw that power, and in-character that's a reasonable thing to do if per your own role you have forsaken the gods. They didn't strip the power from the character, they just stopped giving him it.
tl;dr: It's biting the hand that gives.
Edited 1 time(s). Last edit at 01/20/2017 01:15PM by Murphy.