I don't think anybody said anything about that. It's just that a marketplace based on at least theoretically selling unique copies of artwork can't really exis

I don't think anybody said anything about that. It's just that a marketplace based on at least theoretically selling unique copies of artwork can't really exist in this particular manner. Who made a given piece of art, and who has the right to sell it isn't an engineering issue, and makes no sense whatsoever to do in a decentralized manner.