You seem to be responding to the reverse, “thinking is writing”, which I agree is not true, you can think without writing.

They are making the point that writing is more than dumping a completed thought. The act of doing that helps you to critique your dumped thoughts, to have more thoughts about your thoughts, to simplify them or expand them.

It’s easier to go meta once you dump your state.

I think you are right and I understood it the other way around

Kind of ironic, though - I wrote, but my thinking process wasn't so great :)

Thanks for the correction!