I realized something recently about docs-vs-blogs. An important difference between the two is that official documentation of a project is the place to say "this is how it is done", whereas blogs are a place to say "this is how I do it". If there isn't a consensus on how something should be done, but you think the way you do it is nice, it definitely makes sense to write about that in a blog post, but it only possibly makes sense to propose your way for official documentation.

I think it took all those blog posts to generate all the consensus necessary to make the "pretty decent" (I would say "very good") Rails docs possible.