We already have privacy preserving age verification: the website asks for your age (or just whether you're over 18), and lets you through.

There's no issuing party to collude with to deanonymize users, no hard requirement on owning a Google- or Apple-vetted smartphone, and generally no way to identify me besides my choice of random numbers.

You move past that, and people rightfully tell you that your scheme outright breaks privacy, or that it makes too many assumptions or is too complex to easily verify it actually preserves privacy.