A documentation tree does not need to begin with a custom database model. WordPress Pages already have parents, ordering, titles, excerpts, revisions, permissions, and familiar editing screens.
Docspress builds on that existing grammar. The result is less spectacular in the database and more useful in daily editorial work: an editor can move a Page, change its order, and immediately understand what happens to the reading path.
This is also a portability decision. If the theme changes, the documents remain Pages. Their relationships remain inspectable. The site does not lose its content because a presentation layer was replaced.