Im not sure which of my points you were addressing.
I personally am one of those women that dont care much about the man's physical appearance. But the idea of being with a man 10, 15, 20+ years more than me when i was 18-20s was absolutely repulsive. Now im in my 30s and been married for years, so i dont entertain the thought, but it would probably be less gross because i am less of a child mentally.
Im not much of a "science " person, but didnt they find that the frontal cortex of the brain doesn't fully mature until the late 20s? A 20 year old is in many ways still a girl mentally, even though her body has gone through puberty. While an attraction to her wouldnt make a man a p3d0, there is a huge power imbalance there.
As for it being done that way always, in the past a girls family, specifically her father, would have had a say in who she would marry. Im not arguing for or against said practice, but im just saying that it is different from a modern girl just out of high school getting hit up by a bunch of old losers that couldn't catch a girl in her 20s when THEY were in their 20s.
People in their 40s, 50s etc have little in common with 20 year olds. They are past their prime physically, not just attraction wise but also physical activity level. Men's life expectancy is shorter than women's as it is. Unless he is very wealthy and doesnt force a prenup i just cant see how a much younger woman doesnt get screwed over in this situation, especially if he leaves young kids for her to raise alone. Because now she's no longer a 20 year old woman but a 30 something single mom, and the kind of men that like them super young are the same kind of men that tell each other to avoid women with kids.