Pretending that css works just fine with functional components is as odd as saying jss has it already figured out. I feel like both still have nagging issues. I somewhat agree with some parts, but overall my experience with raw css has been terrible. I totally understand why developers are out trying to fix that considering that vendors have ignored modular styles for so long, and now they’re ignoring declarative components in favour of imperative dom templates.
That brings me to the end of the article, there it gets fuzzy. How exactly will the shadow-dom solve any of the issues we face with css i wonder? A declarative, functional component is not a HTML directive and will never be. I don’t yet see where you see the connection between the two.