I think I already said that in my original post.
> We should not accept the Overton window shifting here
Great! Let's say you and I refuse to accept it. How do we keep Discord from demanding passports or selfies? How can we get France[1] or Finland[2] to roll back age restrictions on social media?
You'll never convince a majority of voters in democracies that nothing online should be age-restricted. These are the people that the enemies of anonymity and free speech are counting on to advance their agenda.
At the same time a majority of voters is currently quite content with the state of age verification for access to tobacco and alcohol. Both its strictness (or lack thereof) and privacy preservation (almost perfect).
I'm not saying my proposal is the one that should be adopted. I honestly don't care which idea gets picked and I don't want anything from it. But it's a virtual guarantee that in the absence of a competing good-enough, privacy-preserving implementation, only the most privacy-invasive idea will be implemented.