As someone who does both a lot of interviewing (at Google) and gives a lot of advice on interviewing to people just starting out, this rhymes with my intuition about why some people get into interviews: even without the use of brainteasers (which, for the record, are not used at Google), the interview process is hard. People rarely come out of it without at least a twinge of frustration of humiliation. I'm not immune to this, I got hired at Google despite having a few interviews where I thought "God damn that was horrible," and I didn't get offers at places I know I was good enough to work at because I wasn't performing at my best for whatever reason and nuked the interviews.

I have a pet theory that when people interview they bring this buried frustration into the room with them and use the interviewing process to play the part of the people they feel humiliated them. It's conceivable that people with latent meanness, or as this abstract calls it tendencies for "narcissism and sadism" who aren't aware enough of their biases to try to counteract them, will use these sorts of questions to make themselves feel better.

Also, and this is probably more specific, there's a bit of a mythos around companies like Google and friends that have tough interviews and high standards: they hire the best people, they're doing the best work, they're the smartest, etc. I can tell you from experience, that mythos doesn't hold up once you're doing you day to day job. I've seen people with stunning credentials doing what most would consider exciting work become genuinely bored. Perhaps for some of them interviewing is a way of reminding themselves of how desirable and high status their workplace is, to the detriment of the poor candidate.

And of course, as a disclaimer, this isn't even anecdote, these are my own personal musings on psychology. Don't confuse this with insight into the Google hiring process.