This is where your thinking comes to nothing.
The logic is simple:
Pornography destroys families.
Families are the building block for our country, and families have always been a primary target.
So do guns destroy families, but your Constitution allows for them. The destructive power of an activity does not affect the right to do an activity. The Constitution or law does not weigh the merits of activity, but treats them both equally.
A man who has raised 6 kids and each of them are doctors, lawyers, teachers, military officers, police officers, etc, is worth more morally than a man who sired 27 kids and doesn’t see them and is an unemployed bum who gambles and cavorts with prostitutes. However, under the law, they are both the same.
The law does not consider merit to be a factor in its determiniations.