[OkayPhysicist]

The pathology about grades is caused by colleges giving far too great a weight to high school GPA. If it falls below a 3.5, your chances of getting into the kind of school that people who give a shit about their or their child's education are gunning for drops precipitously.

Meanwhile, universities don't take the time to seriously consider what courses a student took, save for a few APs. That leads to a situation where it may well be in the student's best interest to coast through an easy A rather than get a B or C in a more challenging course. An example I can think of immediately was a friend who got an offer rescinded from a UC because they failed Discrete Mathematics as a senior, despite the fact that taking the class at all was completely optional for him.