First off, you aren't doing functional programming when you have first class functions or if you use HO functions like map and reduce. Those concepts can exist in imperative programs. The only concept that makes a program functional is immutability. That's it. Functional programming does not make sense to you if you don't understand this.

>I'd say that anyone who's complaining about callback hell isn't up-to-date with the JS world. Promises have fixed this problem and, as you pointed out, async/await make it even nicer.

The latest node api still uses callbacks. Promises haven't fixed this problem, it's just a bandaid on stab wound. Async/await is the proper way to deal with this problem and python supports it so there's no upside for node in this area.