Be nice if you didn't actually have a phone number and you exchanged cryptographic keys with someone touchlessly when you were in physical contact. Then you'd

Be nice if you didn't actually have a phone number and you exchanged cryptographic keys with someone touchlessly when you were in physical contact. Then you'd have two-way ID verification, and if a merchant abused that by leaking their key material (or if it leaked in a hack) you could revoke that key's permission. A large weakness with existing communication systems (phone, e-mail, physical mail) is that its a pipe where anyone in the world can blast at you, often anonymously.