In your example, yes, that plays out exactly the way you described. But why would Arthur and Bob be involved in the transaction at all? The government office responsible for recording deeds would be the ones with a copy of the blockchain. Nothing says they need to make it public, and only other offices from that agency need to be involved in the consensus process. The same scenario you described works just as well if there’s a central SQL db. Either way, the source of authenticity isn’t inherent to the blockchain itself, but to the security of the implementation and the agencies that are providing consensus. It’s not as though the agency in Portland and the agency in Omaha are going to call Arthur and Bob’s local agency to verify the transaction—they’re going to consent to the data so long as the data is valid and shows that the property only belongs to one person at a time. Yes, blockchain does prevent whatever piece of information is being recorded from belonging to two people at the same time, whether that’s money, land, expensive watches, whatever. But it doesn’t add anything to proving whether the owner of record is valid that you don’t get from a well-designed db running on some other platform. Like any platform, it just has certain elements of its implementation that are easier, and certain elements that are harder. All tech is like that.