Yeah, you make some good points up until you ride your favorite hobby horse off a cliff. And that point might be a valid one if test scores and GPAs were perfect or even the best predictor of who would make a good physician. The medical community has come to the conclusion that they do not. I've given you lots of links on the other board so I won't bother with it now.
Of course they're not perfect. No one ever claimed they were. But you're wrong about the conclusion the 'medical community' has come to. 95% of people in the highest GPA/MCAT grouping are accepted into medical school. This demonstrates that indeed, medical schools value achievement and aptitude scores very, very highly.
And I, of course, have never, not ever, claimed or even believe other factors are not relevant or discoverable or should not be used. What I have claimed is that if you are going to use that factor to influence entry, it should have demonstrated predictive validity with success in medicine.
And if certain communities are underserved, it is proper for the Government to offer bonded scholarships for medicine students. You get a free ride through medical school, you promise to serve at a particular posting after you graduate.