Its interesting you use the word "component" about ten times in this post, because that's more or less exactly what Web Components are about - a set of specific

Its interesting you use the word "component" about ten times in this post, because that's more or less exactly what Web Components are about - a set of specifications that will (hopefully/theoretically) lead to much greater interop between all this stuff. Polymer is one of the first implementations of a library built on this spec. Keep in mind though, the environment QT runs in is very different to the web, so most of us poor web devs are at the mercy of browser vendors, and as such we're often limited by the lowest common denominator.