There is no magic other than the unfamiliar. The problem is not magic or the unfamiliar, it is complexity.
A technique can be understood, and still a pain in the ass to use; then it is bad. This is of course subjective, by comparison with other ways of solving the same problem.
Or, a technique can be useful, but too difficult to learn to justify using it on something simple; then it is inappropriate, and should be replaced by simpler, presumably less concise, code. This is of course subjective, dependent on the code's audience (readers, reviewers, maintainers). This is the root of the article's map vs for-loop example: different levels of familiarity with the technique of mapping functions over something.
A technique can be understood, and still a pain in the ass to use; then it is bad. This is of course subjective, by comparison with other ways of solving the same problem.
Or, a technique can be useful, but too difficult to learn to justify using it on something simple; then it is inappropriate, and should be replaced by simpler, presumably less concise, code. This is of course subjective, dependent on the code's audience (readers, reviewers, maintainers). This is the root of the article's map vs for-loop example: different levels of familiarity with the technique of mapping functions over something.