Articles and blogs are far more similar to one another than articles and books, for one thing. For another, you can just write long form articles as blog posts and they will 100% function as a blog. You can even have them presented exactly that way using npub.pro.

Now, if you want to write both blogs and articles under the same npub, and have them presented separately, you would need to have two separate kinds, or else just make two separate npub.pro sites, and manually import the blog notes to one and the articles to the other.