Lack of real-life societies which enslaved all their women should be a big hint.
Think about it for a bit. Half the population is slaves. Somebody has to watch them, guard them, suppress their attempts at rebellion, etc. Your hypothetical society will have to spend a LOT of resources on just keeping things under control while having significantly lower economic productivity. And in the case of war they can't field a large army because a lot of men are prison wardens and can't leave women slaves unattended.
The idea is just very obviously bad and unworkable.
I think this idea of slavery does not match with what historically has been the reality of enslavement. It's not that you need one slavemaster for every slave, or that slaves are kept perpetually in prison.
To have slaves you 'just' need less education, the prevalent idea that they need a master, hard labor and some form of punishment for transgressing. I think this set better describes what has been the reality of (say) women in ancient China or Middle-East, black people under the colonial empires, etc.
But let's just taboo "slave", the main issue...
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