Either way I do believe this may have more affect on general fertility but generally it goes unspoken, generally, because no one wants to admit allowing free and and nearly unfettered access to sexaully explicit material to both adults and minors is a bad thing.
And please don't say, "I care about those things too." You brought up porn specifically. That's why I don't believe you.
> it goes unspoken.. because no one wants to admit
A more likely explanation is that few people actually agree with you. Your argument is extremely common among people using motivated reasoning to try to ban content they don't like, starting with porn.