Both high school grades and test scores load on intelligence. Grades have a higher loading on persistence and diligence than test scores do, and these qualities certainly matter for college success.
Somehow emotional maturity and stability needs to be taken into account, too.
I had high test scores and high grades, however I completely collapsed in college because of a failure to adapt to the social and academic environment. Essentially, I had no ability or knowledge how to self-regulate.
In hindsight, there was no sense whatsoever in wasting a perfectly good engineering scholarship on me.
While I don't know you, your experience shows my point. Perhaps with a broader range of life experiences prior to college your experience would have been different. That's what colleges are trying to gauge using those other factors (Leadership experience, volunteerism, extracurricular activities, etc.) Does this person have the life skills to not only be able to handle our college academically but do they have the persistence, mental stability, communication skills, social skills, confidence, determination, and disciple needed to be a successful college student at this college?
A college student with the highest of all exam scores has little benefit to a college if they don't have the rest of the skills required to complete a degree for starters. If the student has the ability to not only complete the degree but share what they've learned with others as a leader in a meaningful and charismatic way, better yet. Yes, it's competition, like most competitions more than one skill or characteristic is needed to win.
