When we learned about ancient Egypt, it was mentioned that the Egyptian queen consorts had a lot of political power. But since the Egyptian Kings married many woman, some queen consorts were more powerful than others.
If a queen consort's son became King, she had political say and even ruled until her son grew up. But queen consorts who did not have children that took the throne, did not have any power.
This system I think is sort of similar to Ottoman wives. They also did not have official roles but could rule the empire, or could influence their husbands, especially if they had sons in line for the throne.
I think that giving birth to an heir has actually been really important for queen consorts in history.