Not necessarily. Nested selectors make it pretty easy to apply styles in a modularized way. See https://rstacruz.github.io/rscss/
You can limit selectors (not custom properties) to a subtree by using @scope.
On the horizon is @function [1] where custom properties can be local to the function.
[1]: https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/A...
Not necessarily. Nested selectors make it pretty easy to apply styles in a modularized way. See https://rstacruz.github.io/rscss/