Mostly habit but also an allegiance to an idea that the classical ideas have high truth value. Your intuition is correct that these professors are engaging in a different test. Their truth units would be on the supply side--are they checking the boxes of the subjects they think are important. It's a positive test, but they aren't adequately concerned with the "demand" side--how well this is working for students. I would say that their test is not wrong, but it is incomplete.