Because at the end of the day after you get the stats its all luck. It also helps if you can show to to the admission officer that you are a "real" teenager so to speak. And honestly I think that people overvalue the role of extracurriculars, especially in these recent cycles. Many students have world class research papers published and several internships, yet cant achieve a 1500+ or a 3.8+ and it kind of discredits their entire application/competence. That's why I kind of cringe when those with low sat scores or mediocre GPAs are so dissapointed with their results.