It's quite all right to disagree with me - no one but the AAMC knows how or why I got my score. So I prefer to be judged only on the merit of my opinion, not on any qualifications that may or may not be deserved. Sure, I think in practice you may well be right. It might be that if one dedicates enough study time to it, anybody can get 520+. In fact, in my guide posted on here, I think I made that point - people think that getting 520+ is due to luck, but it's really not. But not everyone starts from the same place and it may well be impossible for someone who starts at a low level to dedicate any realistic amount of time to it to get a top score. Sure, maybe if he or she studied for a couple years, but what kind of life is that? Somebody who starts at a higher level, due to prior development of these key skills through years of practice, would need much less time. That's all I'm saying.
I'm sorry you believe that. I have yet to see an applicant get in who has 4.0, 40 MCAT, zero volunteering, clinical experience, etc. This is the pre-med mindset that is so devastating to many pre-meds. There is nothing different in abilities between someone with a 3.7 GPA and someone with a 4.0 GPA - both can handle the rigor of medical school coursework. As someone who is intimately involved in assigning grades to large classes of undergraduate pre-meds, I often see cases where an A- student is actually more able than the A student but suffers a lower grade because he or she wasn't good at taking exams, the exam focused too much on memorization rather than scientific reasoning, the A- student was half a point away from an A but couldn't get it because the professor capped the number of A's given out. In terms of GPA, there's 0.3 gap, but that gap could largely be due to circumstances outside the student's control - maybe he or she got sick and missed two lectures that were tested extensively on the exam. That's why people with 3.7s are just as likely to get in as people with 4.0s, ceteris paribus.
On a side note, why do you think that Harvard's average GPA and MCAT are like 3.8 and 36? Don't you think Harvard could fill its incoming class with 4.0s and 40 MCATs if it wanted? The truth is, it doesn't want to. It values other things more than stats. Stats are only meant to show that you can handle the rigor of medical coursework. Beyond that, they're trying to answer the question of whether you will make a good doctor.