Not just the DOM, HTTP as well. We're shoehorning state into a stateless system, and inventing new crap like WebSockets to overcome limitations of a system designed for document retrieval. The web has turned into the biggest hack ever.
Bigger than x86? I doubt it. It's fine for things to evolve: so long as the complexity is compartmentalised we can forget about it and move on with our lives.
A lot of corporate environments prevent you from connecting to anything but port 80 and 443. Websockets is the only way for you to multiplex your tcp-like connections over port 80.