JJG doesnt write posts. He sits and yells into a text to speech microphone. No one would ever type that much without being forced (like in school).
I used to, but I've changed my habits for the sake of readers. Now I just extrapolate if asked to and stay as brief as possible otherwise. Some 10 years ago long comments/posts were much more appreciated, but times have changed I guess.
Typing up such posts takes a minute or so when you type some ~150 words per minute by the way, so it doesn't really matter for the writer.