I'm saying that DOM through its relationship to HTML has weaknesses that make it unsuitable for building application components out of. "jQuery-enabled div-soup" is an example of how mixing presentation with model and logic yields unmaintainable results.
I have been interested in React.js recently, since it provides an interface to create reusable components and to use them inside a rich programming language with full types. I think that's a better example of a competing idea.
My experience is with building single page apps from scratch, so maybe there's a common use-case (embedding a twitter widget, or a 3rd party comment system in a blog) that Shadow DOM and Custom Components will address that I'm not familiar with.