Many people seem to misunderstand trust minimization.
It is not just about preserving developers' anonymity for whatever reasons. If trust approaches 0, potential liability approaches 0. It is an alternative solution for small start-ups: if you can't prevent the code from running, you are either not liable or significantly less liable.
You can have customer support, but you don't have to, you can have insurance, but you don't have to.
Why would a small start-up need upgradeability? It's a hyper-competitive industry.
To test in hardhat:
git clone https://github.com/SamPorter1984/EIP-3561-tests && cd EIP-3561-tests && npm run test
More info: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-3561.md