title: Why doesn't Polymer use ES6
body: <p>It seems like the React community has heavily adopted ES6 as de facto when building applications, but I realized using ES6 with Polymer is fairly uncommon and doesn't seem to be actively encouraged. I was wondering why this is and if it's considered bad "style" to develop Polymer components using ES6 and compile them down to ES5 with Babel or something?</p>