I don't believe just anyone can be a physician; or maybe the bar to entry is quite high that primarily the more intelligent people do it. In any case, I do think you have to be reasonably intelligent to be a physician. I have hardly met a physician I would call below average or plain dumb.
There are several domains of intelligence. For example, Richard Feynman supposedly had an IQ in the low 120s, but his mathematical ability was very high, possibly at the expense of his verbal IQ. Or maybe he developed this skill since this was his special interest. Some say he did not care for grammar or spellings, however his books are well written. In another case, some people sweat to break a 9 on the MCAT no matter what they do, but easily score 12-15 on the science sections. Again, it is not clear if this is due to IQ or years of honing scientific reasoning at the expense of verbal reasoning.
Overall, it appears that some people are multi-talented/gifted in multiple domains, others not as much. However, as long as one works in an area that matches his/her talent, which can be difficult to know a priori, the difference in domains should not matter in the long term. This is why some people are naturally better than others in specific areas. Lebron has a great basketball IQ that is unmatched by many NBA athletes who work just as hard or harder, but Lebron will never shoot a basketball as well as Stephen Curry, but both are great basketball players. I think the same is true in specific domains of knowledge and other life's affairs. Some people are really good at technical or mathematical reasoning and will obtain PhDs in physics and mathematics with the routine effort expected in these pursuits, but would struggle with the volume of information in medical school. Some could handle both types of intellectual demands with the typical effort.
By the way, getting a 260 does require hard work and intelligence. These people are not unintelligent, but maybe their intellectual talents were not matched to the previous standardized tests they took. I know a former med school buddy who scored 28 on the MCAT and slightly above average on the SAT, but scored >260 on all steps. He also scored in the top 10 percentile nationally in his specialty. He won multiple awards in his program, published well in his field as a resident, and was well regarded at a top department where he trained. His prior testing clearly did not predict his future performance in medicine.
I think your friend is the exact type of person I was talking about before. I think there are a few possibilities.
1. Your friend may or may not have applied himself fully before, and therefore the more general aptitude tests, such as the SAT and less so the MCAT, did not fully measure his ability.
2. Your friend had poor early schooling which rendered his reading comprehension and deductive reasoning skills below what they could have been at, and he caught up later on.
3. Your friend has a near photographic memory. This would help on those other tests but not nearly to the degree as on the licensing exams, where ability to retrieve discrete facts point blank is of prime importance. This is why many of those prep books, especially for STEP, aka First AID, is filled with mnemonics for crap like lymph nodes, embryology, HLA markers, and what structures are retroperitoneal.
4. Your friend has an absolutely insane work ethic.
5. Your friend has psychological issues, such as test taking anxiety, that affected his performance early on, but he learned, over time, how he could largely overcome those issues.
6. Some combination of the above
What I find a bit sad is that many of my friends, especially former engineering/math/CS majors and even a few philosophy majors, really struggle with medical school standardized tests, despite breezing through other standardized tests early on in life. Of course this is not always the case. But this group seems to be disproportionately represented among those who did well in the past but less well in medical school.
Just anecdotal and not sure how it fits into the discussion: Most of my friends that were brilliant at math/physics/math heavy econ/CS/philosophy could take biology classes and still do pretty well, maybe they wouldn't get an A but they would get Bs. On the other hand, I knew plenty of premeds, some of whom are currently in medical school and doing well, that failed to even crack a B in entry level physics or Calc 2.
I've stated before that "medicine smart" doesn't necessarily mean smart in other areas. Different posters have fervently disagreed, stating that they only knew of those with visibly autistic tendencies that seemed to do well above the average in medicine and were relatively mediocre performers early on in education, all things held equal. I am glad that others have noticed people who happen to pretty much be exceptional (relative to other fields) at medicine/biology yet are "normal."
I think people who happen to be genetically gifted at one specific thing and enjoy that thing are really lucky. Their skill set is at near max utility.
I just want to say that I love the mostly respectful tone throughout this thread. These discussions an get very emotionally charged in real life. Everyone here has been really mature. Thanks guys