A way this could be implemented is from the Administration\System Security page. It already lists each user based on license type. If their name could be linked to a page that would shows which processes a user is a part of. Another ask for this is to also show which processes the user has been assigned access rights to.

I understand that the best practice is to use groups, but there a lot of customers out there where that isn't the current status of their system, and this would really help manage them until they are able to update them.