Earlier quoted context omitted.
The problem with markdown is that it's not extensible and that there is no spec. Essentially all READMEs would be better off using typst, they would make for better READMEs.
Of course it's extensible, you can put HTML in it, and HTML is extensible.
You can do some pretty wild stuff with html. But if you do, you get an unreadable jumble of markdown and HTML. It loses the single advantage of markdown - which is that its human readable as a text file.