Because, unlike moralfags who make everything about "WHAT ABOUT CHILDREN??!" some people have been around enough to know how online payment processors are a major battleground for freedom of access to all kinds of things, not JUST porn and there's no compartmentalizing it.
There's this site called "Kiwifarms". You might have heard of it? Anyways, they have almost been choked off the internet more than once because Troons and Puritanical Retards have managed to compel payment processors to not honor payments to it simply because they find the content objectionable.. If you can now legislate how payment services do business ON NO OTHER GROUNDS than moral objections, you've just kicked open the door for the next level of censorship.
Porn will continue to be everywhere on the internet, regardless if you have Age verification on Pornhub. There is no way to capture ALL porn and lock it away from Timmy Dipshit 12 yr old with an Ipad if the parents simply don't give a shit. No, I don't think kids should have free and unfettered access to porn, either.