I can create articles as a sub-articles of another article, but when I want to move an article, only categories are listed as targets.
In the move to menu, you have to search articles if you want to move an article to have an article as parents. Only categories are in the tree displayed for quick selection.
Ah, thanks, that solves my problem. I'd still argue it's unintuitive, but at least now I know how to navigate the unintuitiveness.