The book about Esrolia is pretty thin from a character background point of view. So it's a rich field for the invention of more Gloranthan background. But it seems to me that Stafford wanted room in his world for very different societies. Look at the trolls, how's that for different? And part of the charm of Glorantha is that the players find adventures where two or more of those societies touch.
So re. women in Glorantha - there is room for any status you want to play in, certainly somewhere but actually most places.
But getting down to particular cults: From my original RQ GM, who seemed to have studied Glorantha pretty well, i understand the cult figure as an archetype. A cult initiate's goal is to become a better (fill in cult name here).
And Ernalda is an archetypical historical/real world Bronze Age earth goddess. They were very popular in their time too. Which is not surprising given that Bronze Age folks were mostly farmers, so being a priest of a goddess of grain looks like a pretty good gig if you are set to go into the religion business.
But that doesn't mean there is no room for other female archetypes, nor that the whole world is patriarchal.