My concern was that there were two ways of doing the same thing and supporting both would just double the work for everybody, so we had to pick one.
The /.well-known/nostr.json HTTP request is better because
1. a single provider can host infinite names
2. it's still simple and free to host a static site once you have your own domain
3. it could be expanded with more metadata if necessary
Web support was a thing but I've implemented it with DoH which was good enough before deciding to switch to the HTTP.