[tchocky]

And how do you want to prove that the copy you made had the same content that was stored behind the URL? What if the host changes the content behind that URL to something completely different. No one can prove that it's actually the thing you copied that was behind this NFT. It's really worthless in my eyes.

[miracle2k]

A hash of the bytes is really is really useful for this kind of authentication. But for actively traded and popular NFTs that isn't strictly necessary. The community knows what they represent.