This was always the primary role. The only people who ever said it was about writing just wanted an easy sales pitch aimed at everyone else.
Literate programming failed to take off because with that much prose it inevitably misrepresents the actual code. Most normal comments are bad enough.
It's hard to maintain any writing that doesn't actually change the result. You can't "test" comments. The author doesn't even need to know why the code works to write comments that are convincing at first glance. If we want to read lies influenced by office politics, we already have the rest of the docs.