I agree with what you are saying. I think what has changed is that having a harem is no longer socially acceptable. People still cheat all the time, but the era when a high-status man can have 20 "wives", and in which a lot of low-status men (to be made soldiers) can't find any, has ended in the civilized world.
Humans are probably "naturally" polygamous and violent, and also willing to enter violence if it can increase sexual access. This is "good" for the "selfish" genes, but painful for the organism and outright bad for society, which is why societies steer toward mostly-monogamous arrangements as they mature.
I think that there still are very high status men in this world who get away with 20 "wives." Consider, for example, the royalty in Saudi Arabia. My point was it's rare now, and that it was equally rare then. Or do you have stats on it?
There certainly are such high status men. But compared to the world population, and considering they reign over only very small parts of the world, are they even statistically significant?
Humans are probably "naturally" polygamous and violent, and also willing to enter violence if it can increase sexual access. This is "good" for the "selfish" genes, but painful for the organism and outright bad for society, which is why societies steer toward mostly-monogamous arrangements as they mature.