CoffeeScript is not a language worth learning 15 years ago
Even accepting the basic premise of the article, that CS doesn't strictly give you anything you can't get with JS, I still don't see any of the reason explain why I shouldn't write CS instead.
Even if there are no language features CS gives me over JS (and there are -- list comprehensions to name one), I get cleanliness. The Sapir-Whorf hypothesis is just as relevant in programming languages as in human languages. Equivalent JS being "possible" is not a reason to not write easier to understand and more maintainable code with a language that lets me expend less effort to arrive at the same place.