The point is that the sections are (with a couple exceptions) not about content. They're about form.

Is this ideal? I am not inclined to argue so. I believe, ultimately, we'd like to get rid of sections entirely (concretely implemented as close all but one section) and use a system of tags to indicate topics and form, and whatever other attributes we might think of. Until then, sections aligned by form (or "mode of discourse"), with individual posts tagged with keywords in the title, seems to me to be a very workable solution.