The thing about web frontend development is that it suffered from the browser wars and having to appeal to amateur developers. Amateur developers love "Worse is Better"[1]. Basically sacrifice all consistency in favor of simplicity and getting started quickly. "Worse is Better" makes things simple to the point of making ugly hacks for certain situations that don't fit that extreme focus on simplicity.
The browser wars made everything horribly inconsistent. Microsoft's strategy was to make the most broken non-standard code possible automatically work and everyone had to emulate that.
The most clean frontend development I've worked with was Angular with ScalaJS. Typescript in Angular 2 should be really clean. The underlying web browser stuff will never be cleaned up since it has to be backwards compatible.
[1] https://en.wikipedia.org/wiki/Worse_is_better
Edit: Replaced the JWZ URL with wikipedia. Apparently JWZ has some anti-hacker news redirect code on his site.