> for all its warts, MS Word has an excellent formula editor
Honestly, if you are taking the time to write something up properly, the time spent on the equations is a small fraction. And in most contexts it's just more efficient to use LaTeX anyway, at least for papers, manuscripts, thesis etc. So you save more time. If you are collaborating with multiple people you can use a revision control system and have much less pain that track changes, etc. And no more 30s rerendering loop in Word for no obvious reason once you've added some complex content.
More Anectdata: I've watched multiple people give up on writing a thesis or paper in word due to too many issues, and then moved to LaTeX. I've never seen someone go the other way due to limitations they hit in LaTeX.
In college I used to transcribe my notes into nice pdfs using LaTeX, at one point I had snippets for all the common equations, I wasn't even thinking about what to do to write it down, it turned into muscle memory.
Besides that, Word now has support for LaTeX, it speaks pretty loudly about LaTeX qualities over the "let me look for the line integral symbol in these menus".
Yeah, it has a pretty steep learning curve, but once you get over it there's no better way to write equations.
Obviously, it is not for everyone, as I said, if all you need is a couple of equations, Word point and click equation editor is more than enough, but there's nothing "cavemanly" about LaTeX, it's powerful and once you learn how to use it it doesn't stand on your way.
People with a few weeks of consistent practice writing LaTeX can run circles around anyone using a graphical equation editor.
I knew students in college who could type LaTeX twice as fast as I could write formulas with pen and paper.
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.
What does 'let' mean here? Who is stopping them? (Except possibly journals that want LaTeX submissions—but, as you point out, Word can export LaTeX equivalents of its formulæ.)
I'd like to underline that, for all its warts, MS Word has an excellent formula editor (which even supports common LaTeX commands as autocorrect). I know that it's a radical idea, but if the goal is to let scientists spend less time writing formulas, maybe we should consider letting them use modern software?
ps. MS Word can copy formulas into the clipboard as LaTeX expressions, should your journal require LaTeX papers but you dont want to edit your formulas like a caveman.