But is this actually a problem. Does people go around now and need proof that they bought some property?
Yeah, all the time, obviously. That’s literally what a receipt is. If people did not need to prove that they owned things, then receipts, titles and deeds wouldn’t exist.
I’m going to go ahead and refute this claim.
Blockchains can be used to affect the physical world because blockchains can be used to transmit information. One example would be if the result of a blockchain transaction is sharing important information with a user, say a password, account number, or access token.
But there’s also the more obvious case, you can use financial blockchains to send money. If a system is designed to work with that currency, then it will presumably work with that currency. You could for instance design a vending machine to take Bitcoin, if it receives a certain amount of currency to a certain address, it dispenses a snack. Yes, there is an authority that manages this vending machine, but that’s unavoidable in any case. No matter what the scenario is, someone needs to own the machine and manage maintenance and supply for it.