> there's always a fallback if you lose all the copies of your key: you pay a locksmith to come pick the lock and rekey it.

In the digital world you have Shamir's Secret Sharing. Generate a non-encrypting, non-signing, decode-only key and give a N-th of if to N escrow services. If you lose your key you contact M of those entities and recover the data.

Plenty of tricks have been created in the last two decades to address the problems associated with key ownership, the problem is always the lack of UI and of standardization in general.