The Custom Space User Management plugin was able to give Space Administrators the capability to create and manage Confluence groups through the Space Admin UI. However, that plugin is no longer supported or being developed. We would like to see this type of capability included in core Confluence as it provides a HUGE benefit to Enterprise level Confluence instances. Enterprise level Confluence instances may not have the resources that could be dedicated to creating/updating/deleting groups 24x7 for very large instance. Security for the groups should be of utmost concern as to ensure that permissions to create/update/delete are adhered to.