A sufficiently good mechanism from a cryptographic standpoint, but which from a usability perspective totally falls down because people never do it.
It’s a very worthy goal to make these events rare and scary so that users might actually bother reading those numbers out loud to each other.
This will fail when AI software gets really good at imitating voice in real-time during casual talk, but we're not there yet (or - if that is my threat model, I'll find an out of band way to verify)