Discussions around NFTs frequently involve someone making statements about URLs, followed by a defence along the lines of "every real NFT project uses IPFS, and every real buyer checks this". I picked a random artblock project and looked at its contract:

https://etherscan.io/address/0xa7d8d9ef8d8ce8992df33d8b8cf4a...

The tokenURI is this, which is a metadata URI: https://token.artblocks.io/233000985

The image linked from there is this: https://media.artblocks.io/233000985.png

Unless I'm missing somethings these Artblocks NFTs are all entirely centralised around their servers.