I seem to recall that one of the previous times this set of slides was presented here ( https://news.ycombinator.com/item?id=3093323 , https://news.ycombinator.com/item?id=6596855) , some people commented that they would hire the less knowledgeable candidate rather than the more knowledgeable candidate. I genuinely can't remember what the justification was. A hope that by not knowing the details of the language and how it was implemented on typical hardware, he was a better programmer, I think.