But in the real world it is common to need information from the authorization stage to use in the authentication stage. For example you may have a user login with an email address/password which you then pass to an LDAP server in order to get a userId. This userId is then used in a database to determine with objects/groups they have access to.
A lower latency design would be for the authorization service to be able to work with either. That way those requests could be done in parallel to reduce latency.
But in the real world it is common to need information from the authorization stage to use in the authentication stage. For example you may have a user login with an email address/password which you then pass to an LDAP server in order to get a userId. This userId is then used in a database to determine with objects/groups they have access to.