Writing as thinking
The reason to write things down is not to communicate a conclusion but to find out whether you had one to begin with.
Some opening argument for "writing as thinking", stated plainly enough that the rest of the piece has something to push against.
The observation
The pattern shows up often enough that it is worth naming. It is easy to miss because each instance looks like a local decision rather than an example of anything general.
What follows from it
Once you accept the premise, a few consequences arrive whether or not you wanted them. Most of the interesting work is in deciding which of them to accept and which to design around.
Where it breaks down
Every rule of this kind has a domain. The failure mode is applying it outside the conditions that made it true, which is how good advice becomes bad practice.