Why do we memorize things? There are many reasons, but the first, I think, is that when you have something committed to memory, it belongs to you forever. It becomes a part of you.
At Hózhó Academy, at 3rd grade recess, I asked a third grader casually if he knew the Declaration of Independence. At the drop of a hat, the whole class lined up and was prepared to recite. There was no preparation; they just knew it.