The counterpoint is that no responsible adult tries to have sex with minors.
My point here isn't necessarily to defend it but to demonstrate that you need to be trying harder to avoid dogmatic thinking. Parts of the world still happily practice child marriage, how are you going to convince them?
The posts above talking about reversing the genders are kind of right, but that does already exist: it's pretty common for lower class middle school/highschool aged girls to sell their bodies for drugs, alcohol, or just money. This is tolerated in those communities and is seen as "the thing you do while growing up."