To add to this point, it’s quite likely that the vast majority of JavaScript developers are using generators and symbols, whether they realize it or not. The reason is that your build system of choice will typically have been compiling async/await into a combination of generators and iterators for years now.

It’s probably getting to the point where it’s no longer necessary in a lot of cases, but these constructs that “nobody uses” were able to implement the newer and more widely features long before they were available in browsers.