Having grown up in a time where porn was illegal for minors but trivially obtained by anyone who cared in VHS, I honestly don't understand why anyone thinks this scheme would be useful for anything.
I’m also pretty perplexed regarding who are these people who come up with these ideas. Like, how and where did they grow up? Appeared out of thin air with absolutely zero street smarts? I don’t think I knew anyone so removed from reality when growing up.
To play a devils advocate for a second - when I was growing up(in the 90s) I also saw porn way too early than even remotely appropriate - a friend had a VHS tape that he got somewhere, we had to find a moment in time when his parents weren't home, and we put it on for like 5 minutes, we were so scared we were going to be found out we immediately dumped the tape afterwards and didn't find the contents even remotely exciting - I remember just being really disgusted by it(turns out the overproduced fake 90s porn really isn't a great way to introduce anyone to sex).
Nowadays if you speak to any child psychologist about it it's obvious that kids get exposed to it really early(in the UK it's estimated that nearly all kids below age of 10 will have seen some kind of sexual material already) and they do it regularly.
It really isn't comparable to what we(pre-internet people) had and what's happening to kids right now.
I also want to make it completely clear I'm 10000% against this insane idea proposed here. Just pointing out that it isn't even remotely the same as us watching a random VHS tape.
I agree with you, kids are exposed to porn too early and too easily these days.
I am just doubtful that you can obtain any significant limiting by gatekeeping mainstream porn sites, kids will show each other porn in Signal rather than telling each other "visit www.lots-of-porn.xxx", but it won't change much.
I'm afraid it's one of those cases where we can't put the djinn back in the lamp.
Why, it would be useful as a general register of people, matched with their online activity here and there. You speak as if you never ran a state surveillance agency, or at least a major search engine! /s