Restriction settings can be used for a variety of pedagogical purposes. Primarily, we tend to see restrictions used to differentiate content available to certain groups of students within a course, such as content for online-only versus face-to-face students. However, you might also consider any of the following ideas as well: 

• creating alternative assessments for individual students with accessibility needs
• setting forum access restrictions to a specified period of time to encourage more student interaction
• requiring a passing grade on a practice quiz to ensure basic knowledge is acquired before moving forward in learning
• etc.