I interviewed at Google quite a few years ago and had a similar experience but over multiple interviews. I had 5 interviews slowly getting harder and harder questions. By the fifth interview I got past the first question pretty fast so he moved onto a second harder one that my answer did not seem to impress. After all these interviews they just never called me back again. The whole process was senseless.
It was as if they wanted to find the point at which I would fail so they could stop. I'll probably hate Google forever after that. I am sure they have great people but I am always very interested when I meet someone who works there so I can ask them about what they do and they always seemed kinda average good not amazing.
My experience at Google was that the secret sauce wasn't that it was full of geniuses. It's that everyone was _reliably_ competent and very smart. It's hard to overstate how valuable that certainty is, and how impressive it is to manage that at scale. It enables an entirely new world of employer-employee relationships, including their famous transparency and policies that could (and would) be abused by people too dumb to understand coordination problems. The cost of this is of course going to be plenty of false negatives. (Bear in mind they were a fifth of their current size when I was there, so I don't know how much this applies anymore)
