I can filter incoming communications with my social graph and easily attach a cost/zap for users I don't know yet. No need for an npub on the bitcoin base layer there, no?
Discussion
what happens when 100 Niel Liesmons follow me? which one is real?
adding a cost is the point, 0 friction = unlimited spam, fraud, theft, annoyance, etc.
if it cost real Bitcoin to send email, we'd have less spam (which is what proof of work was designed for)
The one that can sign with my private key.
Not, for example, the one that spent the most sats on his npub.
Agreed with the spam-filter. Attaching bitcoin or proof of work to unknown incoming communications as a "cryptographic wall of energy" (to quote Saylor) is something I need as well. But that is up to me to determine how expensive crossing that wall should be.