Agreed, there's a great formula editor which is very nice if you want to create math presentations in powerpoint instead of in beamer (and I wouldn't blame you, especially if you're in a hurry).
But could you really imagine writing a serious mathematical document (paper, book, thesis) in Word? No Git, no vim/emacs, no plain text? Abandoning the digital lingua franca of mathematical communication? Abandoning the packages written by the sum total of anyone who has worked on anything close to mathematics in recent years? For what?
> But could you really imagine writing a serious mathematical document (paper, book, thesis) in Word?
Yes I could, and I did. My Master's thesis is written in Word and it was pretty heavy on the theory and the formulas. If you're interested it's online on http://e.teeselink.nl/thesis_et.pdf. It's not a particularly stunning thesis in terms of content, but in my humble opinion it's a pretty document, definitely no worse than the average LaTeX-produced thesis.
See eg page 58 (the 70th page of the PDF) for some large formulas. It's not arithmetic but Structured Operational Semantics, but I doubt that matters for this argument. (in hindsight I hate that page and the ones like it - the sheer overload of single-character variables makes it totally impossible to understand)
By the way you said "no git" but Word files can be version controlled just fine - particularly when you're working solo which I was. I used Subversion (hey, 2007) but ok.
I used Word because I noticed in earlier years that LaTeX made my mind drop down into "programmer mode" every time I wanted to accomplish something that was non-trivial. This nerd sniped me and it distracted me from writing the actual content. I ended up with super nice LaTeX themes and definitions and homecooked macros (excuse me for having forgotten the real names these things have in LaTeX, I last used it over 10 years ago), my content sources were super clean, but I spent at least as much time on setting up LaTeX as actually writing. Plus, I found editing large formulas frustrating because I had to find the right place in a fullscreen wall of backslashes and curlies.
Word forced me to focus on the content because everything layout-wise I wanted to accomplish was boring and, mostly, easy.
The only thing that was cumbersome was getting IEEE-style references (i.e. the ones that Bibtex generates by default) to work. It worked out in the end but wasn't as easy as it should be (I noticed that they fixed that since). Also I had zero problems with that thing where Word just doesn't want to do what you tell it to (indents jump, list items suddenly disappear etc, you know the drill) because I only used Word Styles (a bit like CSS classes) and never custom formatting. As long as you stick to that, Word sucks less.
Frankly, this PDF shows that it has been produced with Word. For example:
(a) Full justification without hyphenation;
(b) Chapter 6 ends at page 69, and the next 32 pages have wrong left header; and
(c) Section headers with fake small caps.
Using LaTeX would have resulted in a more beautifully typeset paper.
Your point that you might have spent more time preparing it is subjectively true, obviously, and it seems that in your case Word proved good enough.
But could you really imagine writing a serious mathematical document (paper, book, thesis) in Word? No Git, no vim/emacs, no plain text? Abandoning the digital lingua franca of mathematical communication? Abandoning the packages written by the sum total of anyone who has worked on anything close to mathematics in recent years? For what?