Humans have developed the capacity to communicate with one another through language. The other purpose of language however is to communicate with ourselves.
Writing, a subset of using language, helps us literally see what we’re thinking. When we write, we’re leaning on the strongest human sense to make sense of our thoughts: namely, our vision. Compared to our other senses, our brains have the capacity to receive a lot of information via our vision. Using visual cues (and by extension, spatial cues too) is like using the brain’s natural mapping tools to make new knowledge adhere. The famous example of remembering a string of numbers caps the average human at 7 numbers, unless they use mnemonic tools like memory palaces. Suddenly the capacity for retaining numeric information increases, because we’re leaning on visualization techniques that connect the random numbers to visual meaning. That connection is a shortcut from something memorable (the layout of a palace) to something hard to remember (a string of numbers). Our brains are made for making connections.
However, retention of random information is a poor use of our brains. Brains should be used for creative and fun things, such as digging into ideas, and spreading them.
This is where writing really shines, and why I write.