> I don't know why HN rails against it [ZKP for age verification] constantly

Because on its own as often presented, it still has the glaring shortcoming that anybody can proxy an ID verification for anybody else without any form of accountability for having done so. Which means that the only way for it to actually be secure is for the implementation to also required locked down computing devices. Hence why the EU scheme insists on proprietary Apple/Google devices, and why Google research has written nerd sniping blog posts to market it.

There, now you know!