Earlier quoted context omitted.
React is simple, not complex. Simplicity is like the main benefit of using React if your intention is to build a single page app. If that's not what you need, then yeah, use Rails.
React in a vacuum might be. React in the context of building a real application is not.
Of course, if all you're building is a static web page then I can see just using some HTML and CSS. But if you want to work professionally as a web developer then you need to know javascript and at least one major framework. You can not stay employed as a "full stack dev" if all you do is write an a couple HTML and CSS files and serve them with python httpSimpleServer.