I will mint NFTs of your comment, $300 pop so anybody who wants to prove you wrong can do so by buying the NFT of your comment that will surely age well. :) /s
Is there a difference between buying a "comment on HN" and the text of that comment?
NFTs require at least one of two centralized services to remain functional - the original URL and the Opensea cached URL. So proof of ownership is decentralized, but the actual image is not.
People can then choose to value that ledger entry, or not.
Everything else, such as the ability of n app to figure out an image URL for the NFT, is just sugar on top.
NFT people will value a Bored Ape token whether the URL is valid or not - and they are entirely right to do so. The Cryptopunks don't even have a URL!