I tend to agree with this broad idea. Although I don't think it's because it was left out or someone didn't do it. I think it's because it's REALLY HARD™. This is certainly the problem that React/Vue/etc are trying to solve. But I think web components never lived up to the promise because as an industry we simply haven't solved that problem yet. OOP possibly came as close as we've come. The various JS frontend frameworks have also been a decent attempt, but I just don't think it's good enough yet.
If I had to guess I'd say that FRP, functional programming's take on it, has the best chance at succeeding here. But I don't think it's quite there yet either. And even if it was, you still also have to confront the fact that the HTML/CSS split doesn't completely live up to the goal of the style being completely independent from the markup.