@teabiscuit I think before people started preparing/studying for SAT/ACT, they were both good indicators of intelligence. I think they still are, but to a lesser extent.
GPA isn’t a great method, either. Some factors unrelated to intelligence like lack of ECs, little need for sleep, weak schedule, and being able to kiss a teacher’s…play a major role in giving unintelligent people high GPAs, while the opposites of these factors can lower an intelligent individual’s GPA.
The worst part about simply evaluating GPA for colleges is that it’s done differently everywhere and no two schools have identical difficulty. This becomes a problem when only one or two students at a school apply to a college, for their GPA can’t be compared to their respective class.