Many companies instruct candidates should study for interviews with specific books or courses (e.g. “Cracking the Code Interview”).
That indicates the idea is not that someone who is a competent professional should pass without studying. The passively hostile whiteboard coding exams are more like a hazing ritual than an actual job performance test.
I prefer that over being ambushed by unexpected topics. Here, you measure ability to learn, at minimum. Unfortunately, you measure also how much free time candidate has. Which is still better then having candidate to guess what is popular now or which if competing preferences your company has.
That indicates the idea is not that someone who is a competent professional should pass without studying. The passively hostile whiteboard coding exams are more like a hazing ritual than an actual job performance test.