User Source from OIDC

Looking for some schooling on Identity Providers vs User Sources in the gateway. I have an Identity Provider setup and working using OIDC. I want to rely on that provider for user and role management as it abstracts security away from Ignition and onto the enterprise level.

However, when it comes to configuring Alarms etc. it seems like I have to also configure Active Directory or a database to populate On-Call Rosters. This seems redundant?