Currently its possible to apply a restriction to individual course sections so that only certain users can view that section.
It would reduce the administrative burden if moodle was to enforce that restriction on every activity/resource/assignment setting within that section and any new content or activity added afterwards.

At the moment it appears the content in a section is hidden but admins have to make sure that individual activities also have restrictions in place to prevent issues where the user is restricted but may still see an assignment in the gradebook or think they need to submit something but can't view the activity itself

Its also possible that its just a matter of updating the documentation to clarify what happens when you restrict at the sectional level