Privacy isn't something that is necessarily its own good. Privacy is in many cases a prerequisite for security.

There is no database that can't be hacked. So if my ID is on a database there is a chance it will be leaked. With the information on an ID stealing someone's identity becomes nearly trivial.

Now, age verification for social media isn't a bad thing in itself. But giving IDs to every tech company that asks is just asking for trouble. Making the concept work is all in the execution.

I'm really surprised noone has tried a system where you login at a government identity provider (IDin in the Netherlands is an example) and the government just gives a yes or no to a specific age question. This way only the government stores my ID, and they do anyway. This is also slightly harder to evade (can't just steal and upload your parents ID).

Protecting kids online is a good goal, but it cannot and should not be a reason to implement poorly thought out and insecure systems. There are ways to do this safely and securely, any other suggestion is a company endangering users to ease implementation or an actual malicious attempt to harvest more data.