The main reason people started using React is the JSX implementation in React at the time was very innovative. Actually many people working with Rihno in 2006 has talked about using JSX as templating system. FB is just the first one did it. However, now days there are plenty other less bloated front end frame work such as svelte, vue, mithrill that is more easy to use and have JSX support as well. There is really no reason to use React now days.