Using a blockchain to enforce scarcity and authenticity of digital objects is a cool idea on paper but only actually becomes effective under one of two scenarios:

1. Everyone simply agrees and acts accordingly thereby giving the ledger value. See: US dollars.

or,

2. There are real-world repercussions to violating the rules. This implies some form of hybrid blockchain/real-world-contract with trade via blockchain and enforcement via the real-world law.

There are advantages to trading on a blockchain. To make the claim that a digital item (can be simply copied with a screenshot) is "rare" because it's one-of-a-kind on the blockchain only works if everyone agrees that ownership via blockchain is as important or more important than the pixels that make up the image.

The definition of "works" in my previous statement is up for discussion, considering this idea is silly on its own merits, it might be working just fine as far as the creator intended.