Maintaining the access rights for groups in the report manager is a real "pain" if you provide more than only 1 application or report to be selected by the users.
If a new group is created in the system manager you will have to go through all report groups / reports available in the report manager to re-set the settings for security.
Would be at least good to have the option to select all / none rather than clicking one by one through a big list of groups.
They are already managed by system cubes. See feature request: https://feedback.jedox.com/ideas/JS-I-11