> render everything inside a <canvas/> and avoid all of the "build an application on top of a document format" crap that makes web apps so weird to make.

We tried this with flash already. It has the same issues. Browsers provide _a lot more_ than just rendering your html+css. There are cases where it makes sense, but generally, it's a terrible idea. It will be like trying to make a visual novel using youtube in-video links.