The details of his background are not important to my main point and I’ve chosen not to discuss them - how he got in is a separate issue.
The point is, you can’t take non-doers and convert them into doers by awarding credentials.
Medical school was, and to a degree still is, a place where people who shouldn’t be there (at least academically) don’t graduate. The situation with personality and fitness for the work as markers of ability to graduate has, sadly, deteriorated.
I haven’t seen the new MCAT, but in the past it was a pretty good predictor of performance in medical school. Given grade inflation and other contributors, I think standardized testing has an important place.