I do wish that the lawmakers had worked more hand-in-hand with technical exports on more privacy-preserving solutions ahead of enforcing these laws. But Discord is doing this because enforcement has already started.
The Internet is more or less becoming a locked down, controlled and fully observed thing for end users and citizens, so adapting to that world sooner and working within it is just sensible future-proofing.
This also lets them more safely target older users with ads, purchase requests, etc. and new integrations for gambling and other high ROI systems.
No. The whole point of privacy preserving technology is that they don't.
The idea is that the government checks your identity (they know who you are) and give you an anonymous cryptographic proof that you are above, say, 18. They don't know what you do with it.
You give this cryptographic proof to Discord, and they know that if you have access to that proof, then you have access to someone who is above 18. They don't know who you are.
Sure, you could ask an adult to give you a token. But you can also ask an adult to buy you alcohol or to do the age verification scan for you.
If age tokens are truly anonymous, what's the solution for preventing a single person from generating and selling them to whatever child wants one?
Then make it illegal to sell them. Some people will still do it, but children can already order cannabis over the internet.
It's always a trade-off, it will never be perfect. But the status quo is not perfect either. The question is: is it better than the status quo? I think that age verification is not completely unreasonable (as long as it is made in a privacy-preserving manner). As a comparison, I think that ChatControl is completely unreasonable.