There are lots of necessary tasks entailed in a job, and I could test someone on one of those tasks (if it were suitable in an interview context). But there are other things I could ask someone and their performance on that task would be sufficient to hire them. The retort that only necessary skills should be interviewed against isn't a great argument.
Thank you. I meant to address relevant vs irrelevant tasks (soldering =/= roofing, organic synthesis =/= medical diagnosis or performing procedures), but yours is a good point.
(edit: typo) To bring this back to organic chem as a questionably relevant prereq to med school, there are obviously specialties where chem is more or less relevant. I care very much if my pharmacist and anesthesiologist understand chemistry, and less so if my orthopedic surgeons do. To the extent that performance on an unnecessary task is sufficient to hire, the USMLE is a better gate into practicing than an individual med school course grade, and the MCAT is a better gate into med school than organic chemistry. I'm clearly lost in the sauce, both those gates occur after and include concepts from/building on organic chemistry.
That said, organic chemistry is uniquely known as a gatekeeper to med school, more than biology, physics, math, anatomy, and other prereqs. Why concentrate difficulty and training on that component in particular?