Sometimes you need more than a standard website, so you can give an unique user experience to your customers. What about in-flight entertainment, retail store kiosk tablets? In those cases, there is a great solution available - decoupled Drupal with React.
React and Drupal can be used together to create amazing digital experiences. Just imagine that you have an admin interface for your website content (Drupal), a stunning responsive front-end (React) and a iOS and Android app downloadable from App Store and Play Store (React Native) using the same data as your website.
This is one of the strength of decoupled drupal with React.