The blog post has tremendous value to the right audience, no doubt about that. But it's worse than worthless for its actual target audience because the article makes those people feel like they're supposed to get it, and they probably feel shitty when they don't (I did). Even though they shouldn't. No one expects you to read that blog post and get it if you've never used Map or Reduce before. It's misleading and disheartening to the target audience. It's a pretty easy fix. Just change who you're talking to.
When I discovered Array.map, I already knew about map/filter/reduce. The reason it was a discovery is that the bulk of Javascript resources used for(){} loops and in those few places where map/filter/reduce were used, many implemented map/filter/reduce as library functions because Array.map etc were not always part of Javascript...I think Mozilla added them at some point based on how I found out about them.
