huh? OAuth is literally a "delegated authorization framework"
It isn't. OAuth2 really did away with AuthZ and focused on AuthN, regardless of what anyone says.
You have scopes but even those outside of the OIDC scopes are wishy washy and meaningless outside of each implementation.
That's because OAuth in the industry has been changed to only talk about authentication (AuthN) and not (or very lightly) authorization (AuthZ).
And, for the better, AuthZ is so use-case specific that bundling it together with AuthN is just asking for trouble.
Consider AWS and IAM permissions. How would you implement an IAM AuthZ policy system with OAuth? Would you actually want to?
AuthN is a relatively simple process which is why that flow through OAuth (and specifically OIDC) is fairly well trodden and defined. The OAuth Authz capabilities are infrequently used which is why you see them being so spotty.