I don't know if I just became cynical and jaded, but is this really surprising to anyone in any way? Any time I give out my personal information to anyone for any reason, I basically treat it as 'any member of public can now access it'. Even if a service doesn't have it in their TOS that they sell it to 3rd parties, they might do it anyway, or there will, sooner or later, be a breach of their poorly secured system. T…
ZK proofs for identity can't go mainstream quick enough. I agree with what you're saying completely. It's frustrating that we have the technology now to verify aspects of someone's identity without revealing it, but that it's going to take forever to become robust enough for mainstream use.
Think about it - the claim is that those systems can prove aspects of someone's identity (eg age), without the site where the proof is used obtaining any knowledge about the individual and without the proof provider knowing where the proof is used. If all of these things are true while users are running software they can control, then it's trivial for an activist to set up a proxy that takes requests for proofs from other users and generates proofs based on the activist's identity - with no downside for the activist, since this can never be traced back to them.
The only thing that could be done is for proof providers to limit the rate of proofs per identity so that multiple activists would be required to say provide access to Discord to all the kids who want it.