In this great post, Cathy Dutton explains how she removed Sass from her codebase. Why? She explains how she used to use Sass for layout, variables, and typography, but now native CSS features take care of that for her.
I’ll say I’m more or less right there with her, and CSS Variables is a big one. I’d say really the only things keeping me from wiping it out completely are partials and the odd mixin.