you are absolutely right. we should completely throw away the development of browser APIs over the years and develop sites with html 4.0
At least in the old days if CSS or JS didn't load, you still got a semi-usable page.
Turning HTML+CSS+JS into an application platform has been one of the most fundamentally stupid things we've done as a field and we'll keep paying for it for years on end, second only to not adding slices to C.