It's still a frustrating experience for candidates though. If you were to split the candidates into three buckets, with the first bucket being people who would

It's still a frustrating experience for candidates though. If you were to split the candidates into three buckets, with the first bucket being people who would never pass a FAANG interview (can't code their way out of a wet paper bag), people who can pass a FAANG interview but not reliably, and people who can reliably pass FAANG interviews (PhD in computer science or just leetcode grinder), most of the people in the first two buckets would complain about the interview process. As someone in the second bucket, the process feels rather random (eg. passed the Facebook L6 interview but failed the Google L4 one somehow, passed the onsite at half a dozen other companies), which is mostly because it is. Maybe some interviewer really wanted to see a topological sort algorithm implemented in 20 minutes and there's not enough time in the interview to derive it from first principles, or maybe an interviewer felt grumpy that day, and then that's it, better luck next time. Combined with the policy of not telling candidates what to improve on, it's a pretty frustrating experience. Yes, there are reasons for the company to behave that way, but it's still unpleasant to be on the receiving end of it.