This is useful to teachers, administrators, and students as it helps reduce the possibility of unintentional errors when grading. Teachers have many assignments multiplied by their number of students, so it isn't unreasonable to expect that they'll need to edit something after calculating grades. It may slip their mind to REcalculate and/or it puts a huge task on whoever monitors all of that to catch it when that happens. Having a report to identify students with that discrepancy in a class would make that very easy to track and correct before too much time has passed.