Hey - author here. React is just simpler for me to reason about. A app has many pages, a page has many components. I can write components; I can write Redux/MobX code; I can pass data between components. Things work.

But absolutely, my speed of development when using React is lower than when I'm using server-generated HTML in a Rails app.

On the other hand, I can do things with React I can't do with server-generated HTML.