The whole idea is that the government gives you a cryptographic token that proves you are over 18, but that token can be used anywhere. They don't get to say what websites can look at it, because...how would they.
The concern isn't that an authoritarian government locks you out of some age-restricted sites, it's that it locks you out of them all.
The concern isn't that an authoritarian government locks you out of some age-restricted sites, it's that it locks you out of them all.