One killer feature that doesn't get nearly enough hype is uptime. Check out these stats: https://www.buybitcoinworldwide.com/bitcoin-uptime/ The last incident to cause downtime for bitcoin was in 2013. Ethereum has never had downtime.
Another is speed. People like to talk about how slow web3 is, but even Ethereum is super fast compared to a traditional banking transfer. Traditional accounting isn't expected to be instant, so it has a lot of waiting periods and days-long SLAs.
Also trust. Not everyone can trust their local bank or local government. And even if they can, why should the default preference be to have a company with a spreadsheet tell me how many assets they have marked to my name? I'd rather have a decentralized ledger that doesn't require me to place my trust in an individual company or government.
You can't really build these features without some sort of "blockchain". You could try to put together a consortium of companies or individuals to run a shared database with consensus and vote about administration, having it backed by contracts that would be enforceable by world governments. That'd get you 95% of the way there, but it'd still be less good than a public blockchain run by volunteers that provides the same trustless features.