The sass folks nowadays tend to implement things in dart sass, improve the documentation, and then let everyone else catch up. I recently ran into this when trying to use @use in a Rails app and realized that it was still unsupported. It’d be rather nice if we just used Dart Sass.
I think the issue is a bit bigger. More and more things that Sprockets relied on in the old days are essentially dead or outdated now. This includes SassC, CoffeeScript (RIP ), Uglifier and even Sprockets itself to some extent.
Frontend realm moved forward leaving rails defaults a bit behind in recent years. Overall JS and CSS development used to be “simple” or rather straightforward, now it’s not and we need to learn it again.