Components are a designer’s bread and butter. Designers have been building design systems with some model of “component” for a really long time. As the web has matured, from Atomic Design to Sketch Symbols, “components” (in some form or another) have asserted themselves as a best practice for web designers ...
Designers don’t care about selectors or #TheCascade. They might make use of it since it’s available, but #TheCascade never comes up in the design thought process.
(Okay okay... most designers. You're special. But we both knew that already.)
I think James makes strong points here. I'm, predictably, in the camp in which I like CSS. I don't find it particularly hard or troublesome. Yet, I don't think in CSS when designing. Much easier to think (and work) in components, nesting them as needed. If the developer flow matched that, that's cool.
I also agree with Sarah Federman who chimed in on Twitter:
It seems a bit premature to look at the current landscape of component CSS tooling at say that it's designer-friendly.
The whole conversation is worth reading, ending with:
Tooling that treats component design as an interface with the code is where it's at/going to be. Hopefully, designers will be more empowered to create component styles when we can meet them closer to their comfort zone.