Would you want people reading your half-baked essays? I know "I'd be embarrassed to let anyone see this as it is right now" is the most common reason I have for not making code open source -- I wouldn't be surprised at all if PG, for exactly the same reason, didn't want to publish early drafts of his essays.
I've found that there's typically more benefit to be had from sharing an idea, than there is from hoarding it and believing you can perfect it on your own.
When I've done the former, it's been way less painful than I imagined, and when I've done the latter, the project has felt like it was stuck in tar (totally my fault).
