Why Web Components will make the web a better place for our users

One point not covered explicitly by the article is why interop between web components, even built with different libraries, will work well.

Custom elements have the same public interfaces as built-in elements: attributes, child nodes, properties, methods and events.

Any framework or library that can deal with elements, can already deal with custom elements to a large extent, and as frameworks break their closed-set assumptions about elements (like Angular's going in the 1.x -> 2.0 transition) this will only get better.

Even 2-way data-binding, like Polymer supports, is done via property setting and custom events. It's completely usable from plain JS, and will work well with Angular 2 templates.