Prior to ES6, there were hundreds of incompatible class-like implementations in the JS ecosystem, and every major library had its own. That included React. No

Prior to ES6, there were hundreds of incompatible class-like implementations in the JS ecosystem, and every major library had its own. That included React. Now that ES6 classes are actually part of the language, there's no reason for the React team to continue maintaining their own class-like implementation. They can defer that to the language itself. This also enables better use of standardizing tooling around the JS language.