I understand that this is a common belief, but I don't agree that it is strictly true; it is contrary to my own experience, both as an applicant and as an interviewer.
Note that we are talking about a particular interview process which uses CP (Competitive Programming). This is common at FAG (Lets exclude Netflix since as I've heard they don't do it) and at companies that copycat the process. Of course, there are many other places that don't do it.
We are? What is "competitive programming", and where did it come into this thread? All I see upstream from your comment is a discussion of Google interviews and large tech company interviews generally. I don't recall anything particularly "competitive" when I interviewed at Google (or Facebook, or Microsoft, or...); they just had me solve problems, as usual.
That's the point, CP != CS (Computer Science). It is a separate discipline/subject with its own trivia knowledge & tricks. CP uses Computer Science the same way as e.g. Physics or Biology use Math. And CP problems are used in those interviews. https://en.wikipedia.org/wiki/Competitive_programming#Benefi...