[detaro]

Does anything actually implement discovery? I looked at various OpenID Connect implementations a while back and nobody seemed to support it. It's a pretty big user-education problem if you can't just say "you can use OpenID Connect", but have to explain "you can use OpenID Connect, provided your provider supports Extensions X and Y, and they probably don't clearly document that they do, so please just try logging in here and see if it works".

[dwaite]

Quite a few things implement discovery. Most IDPs advertise metadata, and many RP libraries consume it by default. IDPs even motivate them to consume it by rotating signing keys pretty often.

Not many things support dynamic client registration, which means the list of IDPs a site can use are pretty static.