You are assuming schools only care about residency placement and passing classes. Rather Medical schools and the AAMC are looking at the bigger picture.
Here is an excerpt from that paper:
"But the ability to excel academically carries less and less gravitas as the domain assessed shifts from the more purely cognitive to the more clinical and ultimately more professional. If the goal of medical schools is to churn out medical science cognitive experts, then GPA is the way to go. The real world, however, places a higher premium on the superb clinician and professional—at least, so it would seem. But in that real world, there are not a lot of physicians with weak cognitive skills. The majority of complaints to State medical boards may be due to issues of professionalism, but that is only because the vast majority of medical aspirants of lower intellectual caliber have been weeded out by GPA and by the Biological Science and Physical Science sections of the MCAT whose predictive validity trends mirror those of GPA (see Figs. 1, 2, 3). Without these screening measures, a much higher proportion of complaints would be due to cognitive, rather than professional, ineptness"
This chart shows the reason why a large number of schools have jumped on MMI, with your logic they should not care about these correlations because they are not as strong as a the science sections and STEP I but they show increasing trend just like the Verbal Section. Furthermore, these effects seem to increase over time compared to the BS and PS section which diminish.
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