Why is "Lower administration effort when users change roles or leave an organization" a benefits of single sign-on?

Context:

Which of the following is not a benefit of single sign-on?
Increased complexity in assigning permissions to users
Single sign-on can reduce the complexity needed to assign permissions to users because there are fewer identities to manage.
Fewer IDs and passwords for users to remember
Lower administration effort when users change roles or leave an organization
Ensuring a consistent password policy across applications

From: https://docs.microsoft.com/en-us/learn/modules/azure-well-architected-security/3-identity-management

My research so far: https://docs.microsoft.com/en-us/azure/active-directory/hybrid/how-to-connect-sso and https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/what-is-single-sign-on