Digital scarcity is the opposite of universals: things that are either unique or restricted in number, and cannot be copied without losing something. Often this is provided by a blockchain proving that it is globally registered by a particular smart contract, and with rules guaranteeing some properties. This adds a potential for a rarity that did not exist previoulsy.
This effect may also be achieved with the countersigning of content with both private keys. This is now a unique artifact, but not revocable.