Well, seems like NIP-98 lacks some features needed for something like Blossom? Blossom wants to be server agnostic so it doesn't want to include the URL of the server it's uploading to in the auth event. Also, why does NIP-98 use the "created_at" field instead of the NIP-40 expiry tag for limiting the valdiity of the auth event? Would be nice if the two could be formed into one to keep things simple.
This is nostr! No features are lacked. You can do what you want. As I said in the issue, the URL can be relaxed for the URL agnostic use case, i wanted it SHOULD instead of must, for that reason. Wilful violation is fine. All events have created_at. I'm actually fine with 2 ways of doing things. Blossom having its own NIP-98 gives it the flexibiltiy it needs to move fast, without potentially breaking other things. It's good, nostr working as expected 😉