What do people have against porn?

Here’s what I get from most people:
Me: “What’s wrong with teens watching porn?”
People: “Because it’s innapropriate.”
Me: “Why?”
People: “Because it shows sex.”

I understand that it might give them ideas, but would they rather their kids be out actually doing that stuff? Porn might actually satisfy their cravings before they get too desperate & have sex.

Background:
My girlfriend Ellie & I got caught writing porn when we were freshmen. Her parents forbid her from talking to me or Rachel (who was uninvolved), & they still hate us over 5 years later.