The solution isn't to block aggressively or to allow everything, but to prioritize. Put accounts older than the AI boom at the top, and allow them to give "referrals", ie stake a part of their own credibility to boost another account on the priority ladder.

Referral systems are very efficient at filtering noise.

It only works when it’s a true stake. Like loosing privileges when a referral is a dunce. The downside is tribalism.

Who will refer me when I find my first issue. this might be a critical thing that should be top priority, but because nobody knows me and I don't know anyone else you just put me to the bottom. Meanwhile someone evil figures out the same problem and a week latter you discover the "zero day" that was causing so many problems for you was in fact reported earlier.

There is also the possibility that in trying to get someone to refer me I give enough details that the trusted person can submit instead of me and claim credit.

Works only for old projects. What happens with new ones?

This is very short sighted.