Earlier quoted context omitted.
I wouldn’t say React is “hacked together”. Perhaps you are referring to the React ecosystem? Facebook doesn’t build single-page apps with React, so naturally it doesn’t provide solutions for routing and similar concerns, so there is more churn as people are figuring this out together.
Wait, do people use React for non-SPA websites?
That said, when an SPA is called for I'd far rather use Ember and get routing, state and a hundred other things for free, without needing to bolt together an entire front-end framework from parts each time.