But it does matter and has to do with the NFT. If you put a URL, whose content can change over time, the NFT that effectively be changed. At least what it's pointing to.

If you're using a content-address hash, you can be sure that you can always get back the same result from that hash as when you got the NFT N years ago.

Yes, I can see that, but seems completely unrelated to the NFT. The NFT and the content it points to are independent from one another.