You are conflating many things. Nobody ever has expected candidates to produce an answer that would be the equivalent of months of work. Basic CS/Math/AI/Physi

You are conflating many things. Nobody ever has expected candidates to produce an answer that would be the equivalent of months of work. Basic CS/Math/AI/Physics knowledge affords you a starting point that's further along in the development/tweaking of an algorithm. That is NOT the end point. Its simply - knowing whats out there. If you start with "well let me go read about whats out there" you will only have time for superficial knowledge from wikipedia or what have you. Because that starting set of knowledge takes years to accumulate. Testing whether you have this starting set is a crucial setup in knowing whether a candidate is going to constantly end up wasting time reading up on basic stuff. You can't build a plane by opening a high school physics book. One other thing is that when you have a broad enough set of domain knowledge in your head, its much more likely that you're able to connect the dots cross-domains. This is essential if you're going to be doing some interesting algorithmic work. Of course, all of what I said is predicated upon you being interested in that sort of work.