> In this case, the card is an image file and the third party is math (the smart contract that issued the token).
There's no canonical block chain. So the same image can be resold on any number of blockchains and every buyer can claim to be the "owner" with the same legitimacy. Which is zero legitimacy. There's not even a meaningful way to verify the person selling an NFT had any rights to do so.
With a signed baseball card if you have physical possession of it then you're the owner. You have exclusive control over access to the card. Even if the card's inflated value drops because no one is willing to buy it, you still have a physical card to enjoy.
Sure there is. Anytime someone says "NFT", they are almost certainly referring to an ERC-721/777[1] token on Ethereum. What other blockchains support NFTs and have any kind of use?
Re legitimacy: how do you prove that any piece of artwork for sale in the real world is legit (the seller isn't violating someone's copyright or selling something stolen)? With an NFT at least, there's no such thing as a fake bored ape; the contract address that defined those is known. You can copy the image, you can even mint it, but it will be a trivially differentiable from the original, since it will belong to a different contract.
There's no canonical block chain. So the same image can be resold on any number of blockchains and every buyer can claim to be the "owner" with the same legitimacy. Which is zero legitimacy. There's not even a meaningful way to verify the person selling an NFT had any rights to do so.
With a signed baseball card if you have physical possession of it then you're the owner. You have exclusive control over access to the card. Even if the card's inflated value drops because no one is willing to buy it, you still have a physical card to enjoy.