Without writing, you are going to get lost in your thoughts and eventually they will all crumbled down around you when you push too far.
Writing is such a great invention - because it lets you transfer knowledge across time and between people.
However, I find less people appreciate that, without writing, a lot of the complex ideas people have worked through would not be possible. Your brain just can’t hold it all in there.
The paper becomes an extension of you and your brain.