As I explained in another comment in the same thread, it's a far cry from ensuring interoperability. The term "open ledger" is also misguiding since it's just an open ledger of whatever you want to put there, it doesn't necessarily reflect even a representative part of a whole system that would provide some kind of financial service.
As another commenter explained regarding video ownership, there's also no incentive to move any old and non-interoperable system there to begin with.