The arguments are pretty vague, for example > React becomes counterproductive when developing apps that aren't mere demos. I have developed big apps in Backbone, moving very the same apps to React and the productivity went up madly. Facebook does develop apps which certainly cannot be considered "mere demos" and you can see them in action, for example Ad Manager for Facebook on iOS (written in React Native). Facebook…
React itself is pretty simple and very nice to work with. The whole react/redux/react-redux/react-router/react-router-redux/webpack/babel/flow agglomeration on the other hand is a lot more complex and subject to a lot of api churn. But you can actually get pretty far just using React by itself. Don't adopt other parts of this stack until you actually really need them and you can go pretty far with just a few concepts…
Back in the day, jQuery was amazing because it made selecting and manipulating DOM elements easy. But now, plain JS has mostly caught up to that functionality, to the point that it rarely makes sense to use jQuery over plain JS. I wonder if in a few years the same will be true of much of the functionality in react.