Maybe it's just as "bad", or even worse, but it just shows that people with bad grades aren't necessarily stupid.
I never said the people were stupid, but they are categorized that way because they aren't willing to prove their ability. I had a few friends that were too lazy to do their work but were very capable. However, they earned poor grades in many classes and are having to retake them at a community college before going on to a four-year university/college. It's silly to have to retake a class because the student doesn't feel like doing anything in it even though he was able to do the work.
Like I said, either way, the work doesn't get done, and the student does poorly. A person can be the smartest guy in the world, but unless he is willing to prove it and do something with his abilities, he is just as useless as all the idiots out there.