So-called "academic success" is based on a series of formal tests and rituals, just like IQ is. These tests could be useless as a metric of your knowledge, skills or abilities, just like you're arguing IQ is. Unfortunately, when the name of a performance indicator has the word "success" in it, you stop questioning the validity of such indicator, and you start using it as an absolute benchmark instead. This happens even though the trivial answer to "why do you go to school or college" is usually "for knowledge and skills", not "for academic success".