This hurdle will push people away from #nostr, I fear.
The best way to fight fire is with fire, no?
Let a new npub prove it’s “worth” by making block lists public (they already are via a NIP that I forgot the number of).
That way, if I see a large % overlap between who a new user and an existing user are blocking, I can now assume you are more trustworthy.
Also, if I am a spammer, I’m now incentivized to hunt for my own kind (other spammers) and publicly shame them (by putting them on my block list). nostr:note1wfe2rcdxl5eqwmkxefk6z7uxj3vq7lm3y5030lzhmrw8eznl9jus7rxnc6