Learning how to design and build big distributed systems is hard. I don't mean that the theory is harder than any other field in computer science. I also don't mean that information is hard to come by. There's a wealth of information online, many distributed systems papers are very accessible, and you can't visit a computer science school without tripping over a distributed systems course. What I mean is that learning the practice of building and running big distributed systems requires big systems.
ECMAScript 2015, also known as ES6, was a major release that took six years to finalize. Since then, Technical Committee 39 (TC39), the body in charge of developing the ECMAScript standard, has been releasing a new edition of the standard every year. This annual release cycle has streamlined the process and made new features rapidly available.