That's quite an interesting, if frightening, take on it. Assuming a developer knows what `map` does, then I wouldn't have very much confidence in their reading comprehension if they somehow mentally skipped over the main higher order function being called on a three word line of code.
Would anyone expect such a developer to read and parse several more lines of code more reliably, in order to understand the algorithmic complexity? Seems unwarranted to me...
Humans make mistakes. People code review after exhausting days or late at night. Or sometimes they skim more than they intended to. You want to make problems in the code obvious everywhere that you can.
In programming, if you miss an important detail the repercussions can be high. In a million line codebase every idiom that's slightly more complex than it needs to be is going to result in dozens of additional bugs, sheerly because of the increased surface area for making mistakes with that idiom.
I agree with everything you've said here but being mentally exhausted doesn't make it more likely that you can read even more lines of code in a more reliable fashion.
I think the clue to your thinking, for me, is in your description of the `map` HOF as "slightly more complex". Having years of experience with both paradigms, I've found that grokking a call to one of these fundamental building blocks (map, filter, reduce, fold, etc) is nearly instantaneous. We've all experienced reading prose where the author was excessively verbose when the same point could have been made succinctly. It feels the same way reading for loops once you get over the learning curve of these very basic functional constructs. You have to keep repeating that boilerplate endlessly and it's very tedious to keep writing and reading it.
