I don't think you made it to the last paragraph either: > I know many interviewers also didn't get it, and it became just "do you know the trick to my puzzle".

I don't think you made it to the last paragraph either: > I know many interviewers also didn't get it, and it became just "do you know the trick to my puzzle". That pattern of failure is a good reason to deprecate white board interviews, not "I don't write on a whiteboard when i program in real life".