Well, no it isn't. ReactDOM is designed for consuming the output of React and constructing a DOM-based UI. React itself is fundamentally a reconciliation engine. This is why we've seen React move to such places as React Native (React for native iOS and Android interfaces), React-UMG (React for constructing interfaces in Unreal Engine's Unreal Motion Graphics), React-PDF for generating PDFs, the list goes on. You can view more here:
Yeah - my React/Redux links list has a big section of articles that talk about React's implementation, including both articles that dig into the actual React source and implementation, and many "build-a-mini React" articles: https://github.com/markerikson/react-redux-links/blob/master... .
https://github.com/chentsulin/awesome-react-renderer