Yes text layout is fundamentally different in the sense that text layout is about placing lines of text inside a rectangle, where RectCut is about placing the rectangles and doesn’t help much with text. It would be possible to use RectCut for text flow, but you probably wouldn’t want to, it’s more designed for a small number of on-screen panels in an application.

Core LaTeX is concerned with the flow of text in printed articles, and Knuth published the text layout algorithm “Breaking Paragraphs into Lines” http://www.eprg.org/G53DOC/pdfs/knuth-plass-breaking.pdf

Originally, HTML did the same thing, it was used to emulate the written page and layout text into a box. But not everyone wanted their site to look like a printed article, so CSS and new layout modes sprouted over the years. Today there are seven of them: https://developer.mozilla.org/en-US/docs/Web/CSS/Layout_mode

RectCut is fundamentally most similar in spirit to CSS flexbox, and fundamentally similar to a bunch of other box layout managers in other languages and UI toolkits, as you can see from the comments.

I would call that “flow layout”.

HTML includes a version of it, TeX and DTP apps use various versions of it.

Edit to add: I don’t know the details of TeX except that it uses a hierarchical “box model”. I suspect it’s fairly similar to HTML before flex-box. HTML flex feels like a refined version of Java AWT layout managers (a more successful evolution than Android’s painful variant).

The article and parent talk mostly about layout in terms of rectangles and subdividing those into smaller rectangles. The basics like Box and Flex layout are pretty simple.

Once you start adding constraints like min/max size and relative sizes it becomes more complex but still manageable. You’re still only reasoning about rectangles and their constraints.

Adding rendered text in the mix increases complexity immensely. Determining the size of rendered text is a very complex problem space in itself involving fonts, dpi, text flow, code points, LTR/RTL, ligatures and more. It’s not just rectangles anymore.