[Yizahi]

That's I wrote. Sure, it enables data integrity (maybe, but let's be charitable). Now what? How does the fact that token knows about external data prevents that data from being manipulated if needed? Or do you propose banning inheritances, lawsuits and other actions which apply to the real world artifacts just because blockchain can't deal with that? :) That won't happen.

[ahnick]

It doesn't prevent the manipulation, but it does assist in detecting it. If someone manipulates the off-chain data, then when that off-chain data is hashed and re-verified against the hash stored in the NFT on-chain then there will be a mismatch in the hash values.

Let's suppose that the off-chain data is a PDF containing all the information for the property deed. If the hash values don't match then it means the PDF should be disregarded. If the off-chain data was kept in multiple locations, then one could potentially still retrieve a good copy of the PDF whose hash matches and then can be trusted.

Now, just because a blockchain can be used as the system of record for property deeds does not mean one wouldn't need to still have laws and other organizations enforcing that system of record. The blockchain is just a tool that makes some aspects of the record keeping easier and opens up some interesting possibilities as I've outlined in other comments of this thread.

[Yizahi]

We don't need detecting unwanted manipulation (clarification, we do, but that is a small and rare problem), we need to deal with expected manipulation. Let's say I was phished and some tokenbro across the globe now owns the NFT with a deed to my house, initially this info also got propagated into the centralised DB with stores actual data with deeds and related stuff. I go to police, then to the court and they reaffirm my ownership of the house. Then they restore correct information in the CDB. Now everything is all right, excep that blockchain is now outdated and show a tokenbro as an owner of NFT pointing to deed for my house, and hash is of course not matching now. Now what? Code is not law (surprise), and blockchain doesn't override laws. It is technically useless for this task.