OAuth2: Authentication vs. Authorisation

Scott Brady makes a point that OAuth2 is not an authentication scheme, but an authorisation, or better yet, a delegation mechanism. He points out that tokens just provide validated access to any resource: Usually data of a user, but not necessarily; It may even only indicate that an application gets routine access to e.g. write to a log file.

He proposes to use OpenID Connect as the actual authentication mechanism built upon OAuth2.