NOSTR doesnt solve for limiting transfer of identity.
It's okay for bitcoin, because transfer is the whole point, but whats stopping someone from selling their nsec to someone else, or sharing its credentials?
This forces some use cases into asking for names, pics, and other KYCish info.
What use cases ?
Anything related to digital identity. NOSTR isnt a social media app and everyone acts like the best we can hope for is more people coming from twitter to post cats.
What do you use Nostr for that you wouldn't want transferred with an nsec?
Reputation as a seller, service provider or as source of information?
People can rug there quite effectively without the nsec changing hands
