A ledger of possession is certainly a much better model than a ledger of ownership, but it still falls a bit short because frequently when dealing with more abs

A ledger of possession is certainly a much better model than a ledger of ownership, but it still falls a bit short because frequently when dealing with more abstract kinds of property than a literal physical object, like intangible property (intellectual property, mineral rights), immovable property (land, water sources), or property in the actual possession of a custodial third party (money in a bank account, a company in the care of the board of directors), a court order can change possession, since there's less distinction between possession and ownership of these less concrete forms of property. So it's fair to say that a blockchain can serve as a ledger of possession of those things that are themselves on the blockchain, but not of any thing that is external to the blockchain.