comment: I would argue that a mitigating factor is that GPA isn't really used for individual classes, but over the whole education. In that time frame, we might assume that a student's course grades will be randomly distributed about their "true competence" in that class, so in fact an 89% student is only slightly less likely to get an A- than a 90% student. Thus, their average grade should tend to reflect that, where they'll both be hanging out around a 3.5 over the forty or so courses that constitute a degree.