The first day at university in the 80s, Computer Science, the head of faculty told us that stats were that only 30% made it to graduation and started walking in front of the first row of the hall. “You will graduate, you won't, you won't. You will graduate, you won't, you won't." Motivational speech or not, at least half of the students dropped out in the first two years. The goal of those two years seemed to be right that: convincing people to leave. Then it got easier and more interesting.

Similar experience in EE, the first year requirements were full of "filter" or "weed-out" courses in math and physics.

The generous argument is that it's only fair to the student that they should know quickly whether they'll be able to get through the material. Failing fast can be merciful.

The truth is probably more complicated. Let's just say that the student population ended up looking a lot like the TA and professor population. Lather, rinse, repeat.