Lets take another monster, Visual Studio Code. Its installation is 72mb, but i get so much more installing it including markdown editor.
I know you're not suggesting everything needs to be perfect. We just have different lines we draw where our UX outweighs things like RAM or disk space. For me, if it gives a great UX, 75MB is a tiny fraction of my RAM, I'd gladly pay it.
Besides, I'm only going to have one copy of this thing running. If it was 75MBx25 or something then I'd be concerned, but 75x1? meh.
Then why are you using Windows (dozens of Gb) and not Ubuntu (<5 Gb) or Debian (<1 Gb)?
(And this is coming from a guy that used to program entirely on text editors, because I didn't like how bloaty Eclipse was... I'm not deaf to your plight. I'm just curious that the idea of others making trade offs is so foreign to you.)
Why install a single-purpose Markdown editor when you already have VSCode installed that is an excellent Markdown editor plus a lightweight IDE for nearly every language ever?
One tool, one job is fine for things that actually stick to the Unix principle and keep it lightweight and minimal. Single-purpose apps should be aiming at the 10MB mark, not 100MB. At 100MB+, you can probably find a multipurpose app to do the same job just as well if not better.
Because life is short.