The simplicity has nothing to do with it. For example, if you happen to be a very introverted person, then the social awkwardness of working in front of someone you don&#x27;t know is enough to disrupt all your thinking abilities significantly. You&#x27;re not only worried about the technical parts of the problem, but you are also worried about things like, &quot;Oh god, I typed that semicolon in the wrong spot. This interviewer is going to think I&#x27;m an idiot...&quot; and it&#x27;s incredibly distracting.<p>This is a normal mode of self-conscious thought for a huge number of people who are otherwise excellent at their jobs and perfectly functional (e.g. introverts).<p>Plus, after you&#x27;ve worked a job for a while and know your team, know what&#x27;s expected of you, and can get in the zone with some privacy, then these thoughts no longer really affect you. So they only play a significant role during an interview specifically because the interview is not at all a realistic representation of what working will be like.<p>I find it incredibly disturbing that you see fit to infer anything from the author&#x27;s so-called &quot;inability&quot; to program &quot;under stress.&quot; When someone makes that kind of inference, I think it says a lot more about <i>their</i> dysfunction as a colleague than it says about the other person&#x27;s programming skill. Even if this problem had been Fizz Buzz or swapping two numbers, it&#x27;s so, so far from simulating what a real work social situation would be like that it renders it useless for assessing the candidate, no matter if they answer it perfectly or fail completely. It&#x27;s just a useless scenario.