Many schools, particularly law schools, give an overall class rank based on GPA. While David's point has merit, it would mean that recruiters and HR professionals would have to acquire more information from a transcript than before -- GPA is popular because it is supposed to contain much information in one number. Use of rankings admits that the information content of that number has been reduced by inflation (just as price inflation reduces the information content in changing prices for milk or gas.) Nevertheless, if the demand for information on relative student academic quality is high enough, it will be worth it for employers to sift through the ranking data.