Why not (also) use hash for an NFT?

Hello! So i was wondering why most people when using the ERC721 standard use a link to the media that they want to create an NFT of. Wouldnt it be much safer to (at least also) include a hash of the media that it is linking it to? That way there is at least some kind of protection that the media isnt just changed. Anyone can just hash the file to check.