You are arguing for pedophilia. This is illegal. Most of us, myself included, believe that it is one of the most disgusting of crimes.
I don't know if you are willing to listen to victims of this. Often the adult (I want to use the word "perpetrator" but I am trying to stay unemotional) convinces the young teen that this is something they want. That doesn't make it any less traumatic. There are many adult survivors who can explain what they went through.
What you are describing is a crime. And given the trauma it inflicts on young teens it should be.