When I was a student, I was pretty sure that the policy stemmed from back in the day when calculators were the size of laptops and no one had them but lazy students.
The idea at the time would have been that in the real world there weren't calculators everywhere so you need to do everything by hand.
And that the policy simply hadn't changed in the intervening forty years.
When I worked at the university, I saw how it worked, how corrupt and inefficient it was and this hunch became an absolute certainty.
Well done, atios.