I would have to write an article myself to hit on every point. I agree with you on some of your points. However, there actually is a reason in some circumstances for society to frown on relationships with a twenty year or more age gap or even a ten year age gap depending on how young the other person is.

The thing is, there is still a predatory element to a middle aged person dating a late teen or early twenties. It should not take a scientist to see why and yes, there are very logical reason for parents or others to be concerned about it. The older person's brain is fully developed, they have more life experience, and most of the time are more indepedent.

They win most of the arguments, can be more manipulative because of their experience, and have usually been through a relationship or two, so they are more willing and able to break up and deal with the emotional consequences than someone who is basically still a child emotionally speaking. There is rarely equality in these relationships. There is almost always a power imbalance.