That's something that confused me. Multiple times this season Daenerys has brought up how hard it is to rule as a woman...

Olenna.
Cersei. Daenerys. Yara. The people of Dorne revolted against the male ruler to replace him with Ellaria. I think even the Khals were under the Khalessis right? Like the men lead war and the women lead the rest of society?

The people seem pretty happy with a female ruler.

The only real "we can't be lead by a woman" I can think of in the entire series was the Ironborn moot. The Ironborn people are completely fine with it, she just went back and retook the island with no resistance. It's just the moot which had a problem.

If you want to make something a plot point, you have to actually build it up. This entire series has been "look how powerful all these female leaders are."