That's the point. It's literally a gender flip, women have more physical power which makes them powerful socially, which creates "lower class" needed to maintain power, and that class itself supports it and is disorganised because they're systemically and individually punished for trying to get out of assigned roles (which is upkeep, beside other things) and some find comfort in it.
IRL CEOs don't have to be men, but most of them are, not because they're better and not to imply that it's not difficult, but there's a percentage of additional difficulty on every step of the way that they're less likely have to deal with because they're not met with "could a man be a good CEO?" but "could THIS man be a CEO?".
And just to be clear, I'm not implying that the MC has it good or that men of this manga's world have it good but precisely that it's shitty and unfair, yet for some reason it's what people currently have to deal with.
IRL most MEN are CEOs because men WANT to be CEOs and they're good at it. It requires a high level of competition, sociopathy and aggression to be one. These are traits women on average don't have, thus they have no desire, drive or need to be one. The existence of testosterone and estrogen means that men and women aren't going to want/strive for the same things. Boys and girls LITERALLY focus on different stimuli from birth. The fact that every dominant society on the planet functions like this means it's not societal suppression, but a feature of the human species.
My point is that this isn't some random hand wave fantasy isekai gender swap. The turn happens in the modern age in our world. It doesn't matter how powerful these women are because they can get these fruits. Not EVERY woman is going to want nor care to do so. Not every woman is going to back or condone this type of societal change, just like MEN today don't support or accept the suppression of women.
You can't just create an underclass out of thin air. Education especially prevents this type of treatment. That's why you limit education and access to technology. You have to erase every facet of the old society and educate them from the start that THAT is their role in life.
Otherwise you have normal people who remember the Old Days fomenting rebellion. My point is these women ONLY matter because they have the power to fight demons. They aren't construction workers, they aren't fighting human wars (that we know), and they arent designing, building and maintaining the infrastructure or tech that makes the world run.
MEN would still be doing that. A boxer isn't a President because he can knock someone out. Some chick with the ability to fight demons doesn't become the CEO of Amazon because she's strong. Bezos runs Amazon because he's GOOD at it and he makes money. He's a loser outside of that.