Interesting discussion about React and why it is still used. The main reason given is that in React, UI is a simple derivation of state. You create your state, and your UI, and there is nothing more to think about – it is simple.
Another reason I like React is that it puts the programming language (JS) first. As this article states:
Angular, Ember and Knockout put “JS” in your HTML.
React puts “HTML” in your JS.
The above two characteristics of React are also present in Elm, just with a better programming language.