Wait, I thought that was already the effect, no? With men outnumbering women by a good margin, surely men would try to "out-man" each other to find a mate?
You can't really out-man other men like we used to in the old days anymore.
(i.e. raid another village, kill the men, take the women)
Nowadays we do things more civilized by posing on social media with gym bods and expensive cars and other displays of sexual fitness. Trying to lure a mate instead of taking one.
Unfortunately, the numbers are what they are: a ~30 million gender imbalance. So however you turn it there's going to be 30 million men without a wife/family no matter what they do. Not a good thing if you want society to remain peaceful.
So they either import more women (via force or promise of a better living standard), or they get rid of the excess men (via war), or they suppress them with heavy policing and entertainment doping until the gender imbalance fades out over the next generation or so.
When there are so many men that they know that they will never have a girlfriend or wife in their lives, they stop competing....why go to the gym at that point?
Or the labour export. Iirc, it was a thing in Pakistan a few years back that the Pakistani govt had to clamp down on because it led to domestic abuse and abandonment in many cases.
Average testosterone levels have been dropping significantly all around the world, so this policy likely wouldn't be the cause of the feminization of men.
That paper reminds me of Connections by James Burke.
High incomes leads to better spending on food leading to more cattle production leading to more soy use and more dairy consumption, which leads to more intake of oestrogen in water, leading to lower testosterone counts in consumers, leading to lower fertility rates.
One child policy ruined the life of hundreds of millions of men.