Don't take me wrong - I love SASS. Well, I wrote one of the early Less to Sass translator for Bootstrap (I think around 2009) and wrote Sass syntax plugins for the likes of Coda editor.
However, if I want to build something today that needs to stand the test of time, I know I can write in HTML + CSS and it will be still work (likely) a century from now, without me having to re-install NPM Packages and compile my Sass to CSS. Of course, I might garnish it finally with PostCSS to take advantage of the modern tooling and augment the lacking of current CSS.
P.S. Recently, I was trying to update an old project and looks like Sass deprecated node sass in favor of something new. I'm not even able to keep up with which processor is the right one to use!
Again, this won't work for many projects, but the point of it is long-term maintainability. I assume that most of what is built into major, recent browsers will have the longevity of bottled wine, while technologies outside the browser will be more like fresh grapes. If I want the site itself to be more like the wine than the grapes, doing something with it years from now shouldn't require a tool that no one has used for years.
Even if your point is good, that's just not a productive way to start out.
css-media-vars would be a game changer for me, if it will be possible to use one var and not define many varnames and put them together to one var.
Like your Example:
If it would work something like this, it would be really awesome: Or