I think a lot of that has to do with the language changes that came about with ES2015. Before, we were basically stuck with ES5 and ES3, which aren't that great

I think a lot of that has to do with the language changes that came about with ES2015. Before, we were basically stuck with ES5 and ES3, which aren't that great to work with and limited what you could do (easily, at least). The stuff coming down the pipe (mainly modules, but a lot of ES2017) is really going to get the language to the level where it's going to be natively capable of even supporting a framework on the level of Rails.