Why are there minimum and maximum enrollment numbers for selectives?

It takes a budget to run each selective. A minimum enrollment number is put in place to justify the cost of conducting the selective. A maximum enrollment number is put in place to limit the amount of students registered for a selective. We need to consider room space and van rental space. Additionally, it ensures that each student will have a unique learning experience. Once a selective reaches maximum enrollment, it will be closed to other registrations.