As an aside but still relevant question, why is CSS preferred over JS when these days it can do lots of things like JavaScript and probably uses similar resources.
Couldn't imagine ever wanting skip grid and flexbox for whatever has been concocted up for JS.
That said, there are already aria labels for UI contexts such as modal windows. Desktop OSes are already multi-modal.
2. Without actual CSS JavaScript wouldn’t be of much use for drawing much of anything unless you were just going to use canvasses and forego the DOM entirely