This is so far the most convincing reason for why it is important to commit a lot of (useful) things to memory.
Joshua Foer explains:
Where do new ideas come from if not some alchemical blending of old ideas? In order to invent, one first needed a proper inventory, a bank of existing ideas to drawn on. Not just an inventory but an indexed inventory: to find the right information at the right time.
This is what the art of memory was ultimately useful for.
From Joshua Foer’s Moonwalking with Einstein
Akshat Rathi 