OP didn't say ban all porn, but it should be more tightly regulated and its consumption has proven to be damaging.
Also, I believe there are a number of non-porn sexual education resources, which should stay available.
However, note that the current crackdown on porn isn't about underage consumers, it's about consumption in general. Apple isn't asking for age verification, they are banning adult content completely.
OP said Apple's stance is reasonable and Apple is pretty close to saying "ban all porn".