That’s not the only inversion that blogging entails. When it comes to a (my) blogging method for writing longer, more synthetic work, the traditional relationship between research and writing is reversed. Traditionally, a writer identifies a subject of interest and researches it, then writes about it. In the (my) blogging method, the writer blogs about everything that seems interesting, until a subject gels out of all of those disparate, short pieces.Blogging isn’t just a way to organize your research — it’s a way to do research for a book or essay or story or speech you don’t even know you want to write yet. It’s a way to discover what your future books and essays and stories and speeches will be about.
This is also roughly the way that zettelkasten and commonplace books have worked for centuries.
This passage is an excellent reason for "why" to keep one, which few sources I've seen bother to mention.