Net net it’s probably positive it’s just too easy to spam these otherwise.
The serious researchers all knew how to do this and complied and usually got paid, and the unencrypted stuff was basically always noise we never paid out on.
Probably not as much of a filter now that AI is in play though.
Instead, you'll need something like "you must enroll your pgp fingerprint in our system by sending a handwritten postcard featuring a tourist attraction in your region".
:P
I might steal some variation of this!