The name doesn't help, but while it may produce output out of the box that looks as good as LaTeX, the website also doesn't directly answer another question which matters to people who need to do typesetting things with it that have been solved by others: the huge package ecosystem of LaTeX (and the batteries-included distributions like TeX Live).
I usually need to lean relatively hard on CTAN, and if you’ve got a niche tool with better UX but no widespread adoption in a very entrenched user base, you’re not going to take over.
when i want “texmacs”, i use the other GNU tools: https://www.gnu.org/software/auctex/ , emacs, and pdf-tools.