Don’t quote me on this, but I think it has to do with the idea that your private key (nsec) isn’t a password, but it literally is your account, as it’s the only way to sign an event. 2FA services use third-party authentication, which is centralized.

Tagging some devs to try to get a better answer.

nostr:npub1cmmswlckn82se7f2jeftl6ll4szlc6zzh8hrjyyfm9vm3t2afr7svqlr6f nostr:npub1l2vyh47mk2p0qlsku7hg0vn29faehy9hy34ygaclpn66ukqp3afqutajft nostr:npub1zfss807aer0j26mwp2la0ume0jqde3823rmu97ra6sgyyg956e0s6xw445