I think it's due to the new version of Javascript being released recently after years of stagnation. ES4 was abandoned and ES5 was mainly standardising existing

I think it's due to the new version of Javascript being released recently after years of stagnation. ES4 was abandoned and ES5 was mainly standardising existing practices, while ES6 has added a lot more - new syntax, new types, iterators, generators, modules and so on. A lot of the churn going on is due to people trying to work out the best way to use these new features, along with whether or not to keep backwards-compatibility with existing frameworks and libraries.