This is an honest question, and I'm not trying to pour cold water on DAI. What would happen if DAI had a single centralised source of truth which could be mirrored as needed if people lost faith in the central entity? This is a bit like what Wikipedia has, which is a fully open database that can be mirrored ad infinitum -- but still remains the central source of truth as long as people respect the organisation that runs it. More broadly, does DAI really need to be on a blockchain*? Are there efficient non-blockchain ways to make verifiable stablecoins?
I ask this question because a lot of things that are run on blockchains seem like they're losing more than they're gaining. It makes me suspicious of even DAI.
When I say "fully open database", you might object that this compromises a person's privacy in order to make the database mirror-able. But then again, all blockchains are fully open and public, so there's nothing more to be lost there.
* - By which I mean the Ethereum blockchain, which is inefficient like all blockchains currently are.