Did you ever notice that when a fantasy or sci-fi story includes female priests or female religious leaders, the religion is almost always a pagan or pagan-like one? Why is that? Perhaps it’s because in a lot of a fiction, especially within the fantasy genre, the mythology of a fictional world incorporates or is based on some type of religious belief. Because writers so often use religion to build their fictional universes, it’s possible that when creating their own fictional religions, they feel they need to remain true at least to the spirit or structure of the religion on which they are basing their fictional religion.
I don’t know about structure, but I certainly hope writers don’t feel as if the spirit of my faith, Catholicism, is all just patriarchy and female oppression. Despite this, I have never read, watched, or heard of a fictional religion based on Catholicism which features women as priests, bishops, or even, dare I say, the Pope.