Right; but markdown has expanded beyond that niche. Lots of projects use markdown for other stuff - like mdbook, or for blogs.
I think markdown is a great format for readme files. But for real documentation, the added features of typst are fantastic. Like, being able to write scripts, have figures and custom styling, populate data from JSON files, plugins, typography, numbered sections, footnotes and all sorts of other stuff. Markdown doesn't even support comments properly!
I want typst for blogging, long form articles and documentation. Markdown is great for small stuff. But it doesn't scale.
Ordinary markdowns have had /everything/ you mention for close to 20 years, except typesetting. Academic papers and books, novels, thousands of ebooks, have been written in single file markdowns for 15 years.
Writing directly in typst is good for small things with intense typesetting like ... wedding invitations, advertisements. But it doesn't scale to serious composition by actual writers.
Writing is not typesetting.
All the forms need for the composition of all civilized text were present in word perfect 5.1, which unlike Word, Latex and Typst, permitted no typsetting during the process of writing. They were all recovered in the writers' markdowns nearly two decades ago.
What's the state for generating websites from Typst?
Fascinating Ideas I love hearing opinions on this, it enriches me.
I do belive that atleast simple files like for example READMEs will stay and perhaps are better to stay as Markdown. One advantage that has is that while scripting is cool, It make the document not plain text readable which is a tradeoff one can argue.