Where can I document things? If I put it on my person blog google won't find it - preferring instead SEO blogspam. If I document something but nobody reads it (including me), then the effort was wasted.
Search is only one method through which someone can find what you write. I read a lot of personal websites that I found out about through friends, HN, and links from one site to another.
Case in point: I'm not even going to link to it from this comment. It's easy enough to find for anyone who actually wants to find it :).
I should probably publish more, though.