Good refactoring respects the idioms of the language and the culture of the organisation. Change to new methodology is thoughtful and probably slow, except when a revolution happens but then, its still respectful to the new culture.

Bad refactoring is elitist, "you won't understand this" commented and the owner walks with nobody left behind who understands it.

That the examples deprecated FP and preferred an idiom natural to Java(script) only speaks to the principle. I can imagine a quant-shop in a bank re-factoring to pure Haskell, out of somthing else, and being entirely happy that its FP respecting.

So the surface "FP patterns are bad" is a bit light-on. The point was, nobody else in that specific group could really be expected to maintain them unless they were part of the culture.

"If you unroll loops a la duff's device, you should explain why you're doing it" would be another example.