I think NIP-46 was a pathological case. The bunker:// thing was naturally adopted by all apps and no one bothered to write it in the NIP, it is also necessary for the relay to be included.

There are other things still not written on the current NIP-46 that people are doing (Pablo's "oauth-like" flow) that must still be added there, which is a shame I think, I'm trying to understand how they work first before I add try to add them to the NIP myself.