You're correct, though if I understand correctly, some NFT platforms do provide some (centralized) feature for "unlocking" content. For example, you could upload a full resolution art piece to an NFT platform or any other place and have the server serve the content to any request that proves ownership of the token.

This is a pretty terrible system, though, as it's completely off-chain and not "Web 3.0" or decentralized in the slightest. The server has to store the "private" content in a private centralized database, so the server owners also can access the content, and any hacker could access the database and publicly dump all of the supposedly token-walled content.

It's just taking advantage of the fact that any computer can determine the Ethereum address that owns a particular token and can check to see if a message was signed by that address's private key.

I could imagine a future standard that could maybe integrate this into Ethereum proper, though I'm not sure if it's technologically possible.

There's no way to prevent someone from just publicly releasing the art, but one could imagine some system like the full resolution piece stored as a public key-encrypted blob in the blockchain which can only be decrypted by a token holder.

Maybe upon token ownership transfers the key could be encrypted with the token buyer's Ethereum address public key, though I'm not sure how or if it could work since I think the original content key would have to stored on the network in some fashion in order to later encrypt the key for token owners. So it might not be possible even in theory, though I don't know nearly enough about Ethereum and cryptography to say with any certainty.

The author cares. They got real cash for signing a meaningless token.

So why not ask for donations or sell prints?

It's like owning a celebrity's autograph. Some people do care, a lot.

Except it is different in a way. Owning a physical autograph is different from owning a picture of one; the physical autograph can't be reproduced and has value due to its uniqueness and to its physical existence.

It would instead be like owning a unique piece of paper with a unique number on it, which somehow corresponded to a picture of the autograph. Now the autograph portion is identical between you and anyone else (neither of you has a physical autograph); the only differentiator is your piece of paper. Where is the value?

The NFT is cryptographically signed by the author. You can't forge it, and it's publicly, verifiably linked to the author. It's even better than a physical autograph.

So you'd place value in a cryptographic signature from the author that ties the piece of paper in my analogy above to the photo of their real life signature? How much would you value that at, given that anyone else can acquire and enjoy the exact same photo of the signature that you enjoy, just without the piece of paper saying "this photo that everyone can see and enjoy is owned by andypants"? If the value you'd place on that piece of paper is above zero, why? (Genuinely curious).

Then let’s call it that instead. Rather than pretend it’s possible to own information in the same way you can own a physical object.