Some (legacy) applications are requiring username/password style authentication. This idea is similar or extends the idea "Username/Password SSO to resource servers". The CI platform allows to create additional attributes such as "grouser" , "gsopwd". But leveraging the id_token mechanism (OIDC flow) would require some shared secret between CI and the IAG container, in order to securely transfer the credentials to the back-end application.
The idea is submitted because we need to have this for a customer migrating from Cloud Identity Services to a hosted IAG solution in CI