Perhaps micro wallets should be a thing where your wealth is distributed across many keys mitigating some loss.

If I’m having trouble juggling a single ball, why would it help to add more balls into the mix?

At which point I gained the problem of having to keep track of all of my microwallets securely, hopefully in a way that survives my phone being lost, a house fire, or my untimely death, leaving the wealth to inheritors. All while, at the same time, not ending up behind a single key that has access to all the information to those micro wallets.

Quickly you end up in a situation that either starts to look like how financial companies keep their most high risk keys, or end up outsourcing the whole thing to something that quickly starts to resemble your bank.

So ultimately it's just like cash: Fine for small amounts. Risky, but maybe livable for somewhat larger accounts, or a giant headache that will probably bite you when you start looking at lifetime savings.