I tend to disagree on this, and offer a different perspective: I believe a markdown-like syntax can be way more efficient and RSI-free than a mouse-based WYSIWY

I tend to disagree on this, and offer a different perspective: I believe a markdown-like syntax can be way more efficient and RSI-free than a mouse-based WYSIWYG-like UX. That said, I think both Latex and WYSIWYG editors tend to lure users into unhealthy habits the moment they get over the basics. In the case of WYSIWYG - users tend to spend way too much time on fine tuning every single instance of produced output, which is very much labor intensive busywork. Powerpoint is IMO the canonical example to watch this behavior. In the case of LaTeX/markdown, the somewhat more experienced users get lured into learning more esoteric portions of the underlying system and soon wants to automate everything, by writing TeX or LaTeX macros, hacking emacs modes and whatnot. Arguably, this second mode of wasting time is more intellectually challenging and more fun for some, but maybe just a waste of time still. If one sticks to standard TeX or LaTeX, one can be fast and produce good (but maybe not super spectacular) output.