Presumably whatever 1970s tech they were using previously was creaky and needed to be replaced. It probably had long settlement times. You’re correct that if tw

Presumably whatever 1970s tech they were using previously was creaky and needed to be replaced. It probably had long settlement times. You’re correct that if two extremely trusted parties are going to handle all settlement, you can just have one party run a centralized database. But this gets more challenging when you expand from one party to dozens, and the trust relationships get less clear. Since you’re building a new platform anyway, you might as well build a database that’s replicated and decentralized and doesn’t require trusting any single party for availability and correctness, at which point you’ll either use a blockchain or something functionally equivalent.