The ability to e.g. hold a complicated structure in your mind wasn't particularly valuable for a pack of proto-humans in the African savannah.

Or, having access to paper and pen, it may actually be less valuable now than it was for a pack of proto humans. (The environment was pretty complicated even back then - competing tribes, complex network of alliances within a tribe, the habits of different animals, etc etc. But you couldn't put it down, you had to keep it all in your mind)