Almost nobody uses it because those who might be interested need LaTeX and its packages. This is not LaTeX. (In the future these authors might all be using Typst, but not this thing.)
I tried it some years ago out of curiosity. Did not seem useful.
this is plainly inaccurate. most people only use very few packages, which exists only for legacy reasons, they should be really integrated. TeXmacs provide all things 90% of people need.
I tried it some years ago out of curiosity. Did not seem useful.