“…every pre-med program weeds out, they pretty much have to given the numbers that enter pre-med undergrad and the number of med school acceptances.”
This is a very good point.
There are a large number of students who start at university thinking that they want to become doctors. Most of them are very strong. They are not all equally strong. We want the best of them to end up being the doctors who end up diagnosing and treating our future life threatening diseases. The only way to figure out which of them are strong and which ones are very strong and which ones are exceptional is to give them homework and exams that only the exceptional few can handle.