It's not obvious to me why not. It's a trade-off. You put the responsibility on the user to keep their keys but you save a lot by not spending anything on solving fake or real issues like this.
In this case if you want assurances like this you can trust a third party that handles that stuff for you.
In this case, someone losing their voting ability because of the system on a regular basis is not acceptable. That's the obvious why not. We want to make a system to count the people's votes. If it bars a voter from casting their vote, it's a failure.
> It's a trade-off. You put the responsibility on the user to keep their keys.
Just like for driving or flying or almost any important occupation, we don't only "put responsibility on the user". We have laws against abuse.
As for gold, gold is a commodity, and one that has industrial utility. You can use it for things, so of course, it’s not particularly controlled.
This is the major weakness of proposals to put everything on the blockchain.
In real-world scenarios, accidents happen. Records must be corrected.
Voting is a great example. If we moved voting to the blockchain, it wouldn't automatically solve fraudulent voting problems. It would just record fraudulent votes on the blockchain. If your grandma accidentally loses her private voting keys to hackers, do we just roll over and let the hackers vote as your grandma? Obviously not.
Any future blockchain solutions to anything government-related will certainly have corrective measures and overrides overlaid on top. It's not like we're going to sit back and watch people lose their house because hackers stole the private keys to their property deed, or forbid someone from selling their car because they can't remember the password to their title wallet.