I think the issue is that Harvard vs East Podunk isn’t a realistic comparison people get into. The waters muddy when you. compare say a school generally ranked #25 vs #100. What about vs #150?
As mentioned, input class is often a big predictor for “output” med school acceptance rate.
Basically that gap needs to be quite large (hundreds of places) before it is going to really become a factor in med school admissions.
GPA/MCAT is reductive but holds true generally in addition to experience, volunteering, rec letters, etc. See for yourself via Harvard’s own website: