So I agree that instead of fighting some change that I think is inevitable, they should make it so that it works in the most privacy-conscious way possible. And I mean with real technical solutions, like an open-source app or browser extension you can download, a proof-of-concept server for age verification, etc... using the best crypto has to offer.
If I go to the liquor store, I can't just promise "I'm 21+"
If I go to vote, I can't just promise I'm 16+
If I go to buy a lottery ticket I cant just promise...
I think I made my point.
Either you're old enough to understand what porn is and have desires to consume it in which case you won't be scarred by it and don't need protection from it, or your not in which case you won't seek it out. You need id checks for alcohol because people too young to consume it want it, and given how much teens drink and how not a problem lower drinking ages are in other countries even that claim is somewhat dubious.