I think it would worth it to start over with today's knowledge. The whole stack is garbage: HTTP should be replaced with HTTP2 or Quick, vanilla Javascrip is horrible, CSS feel even worse, HTML is not too bad.
Almost all browsers are Webkit based, and there a very few browsers in use (Chrome/Firefox/Safari) which should ease the transition. I can't imagine all the wasted time and energy the world is putting into the current state of the web. A new standard would make navigation more performant, snappier, more responsive and much more reliable.
There's a lot I agree about starting over, but perhaps one of the main features of the web is its backwards compatibility. Most often when things are built from scratch, they fail miserably, unless one entity has full control of the entire stack. Unfortunately, that doesn't really describe the web. We're kind of stuck with a mess.
Almost all browsers are Webkit based, and there a very few browsers in use (Chrome/Firefox/Safari) which should ease the transition. I can't imagine all the wasted time and energy the world is putting into the current state of the web. A new standard would make navigation more performant, snappier, more responsive and much more reliable.