I used Scientific Word to write my dissertation and my first academic papers. It was a great piece of software in the late 1990s, at least relative to the alternatives, which were writing .tex files yourself or typing in a word processor. I have a coauthor that still uses SW. I can't say this is surprising. I moved to LyX long ago, and then after markdown became popular I ditched LyX and went with that. There are lot…
How does Markdown fill the niche of TeX or Scientific Word? Is there a mathematically oriented fork? You mentioned R Markdown in another comment, but I don't see anything in the gallery that looks germane.
A number of other systems like Obsidian (for note taking) use markdown and integrate MathJaX or KaTeX to render TeX formatted equations.