Further to this point, the shared item is moved to a public key and the infrastructure to facilitate communication. Such that it is not a panacea. Getting away from trust in the system is...
Likely you will envision a system to register your key. And then you have to have a bootstrap to authenticate to this system. Probably a password.
Not my point. Just not clear that the alternatives actually are better. Again, I use hardware tokens. Not seeing my family join me on that anytime soon.
List of problems with every approach always falls back to, "what happens if you lose it?"
And the resolution to that is always outside of the technical chain.
Likely you will envision a system to register your key. And then you have to have a bootstrap to authenticate to this system. Probably a password.