Memorizing facts is the foundation of all learning. When you add 7+7 in your head do you instantly know the answer is 14 because of "understanding" or because you memorized over all the years.
Also the current US education system strictly deemphasizes memorization. Instead it pushes for "understanding" (conveniently a concept that is not measurable).
> Like anybody doesn't have multiple calculators in their pockets.
Ok and?
China and India are producing the smartest people in the world and their education systems strongly emphasize memorization. Understanding comes when you've memorized enough information that you can connect the dots.
Once you get to advanced math it's basically impossible to understand from the start and you can only rely on memorization until you've memorized enough and experienced enough that it finally clicks.