Disclaimer: I do not agree this take was made in bad faith. I think that raising a kid comes with its own set of expectations around caring and curating experiences of said kid. Therefore, I do think that offloading that responsibility to the state (and by extension, businesses that offer age-gating tech to that state...) is not the right way to do it. And even in the absence of that, my experience taught me it is entirely possible to grow up with unsupervised internet access and turn out an OK adult. The internet is not only "depraved porn". It is also a lifeline for that weird kid who has been bullied and effectively barred from social experiences.

Of course, YMMV.

That said, if such a nanny state is inevitable: zero-knowledge-proof-based age verification would not only be possible, it would further protect these kids from a bad state actor. In that spirit, I agree with your last point. The fact that any other alternatives are even being considered makes it on principle a non-starter to me, because it betrays the actual goals of the political actors involved.