It would be very useful to have a feature to administratively disable (block) user accounts to prevent them from logging-in even if SAML or any other non-password authentication way is used.
The rationale behind that is, for example, a case when some business data in the system is related to the Users collection (creator of invoices, author of comments, etc.) When an employee leaves, if their account is deleted, the corresponding references is also lost. Disabling the account instead of deletion would help to keep references.
I am sure that there can be other reasons for disabling accounts without deletion (temporary legal blocks, maternity leaves, etc.).
Please consider adding this functionality in future if possible. Thanks!