Indeed, I don't write off whiteboard interviewing altogether - if you know exactly what you are hiring for, it can be very helpful to have e.g. a systems engin

Indeed, I don't write off whiteboard interviewing altogether - if you know exactly what you are hiring for, it can be very helpful to have e.g. a systems engineer write out some C code or go through tree problems. The issue comes in that a lot of people aren't entirely sure what they are hiring for, just that they need a warm body who can code to some arbitrary ability. That's why I always make sure to ask the interviewer what the burning problems are and what kind of action they are looking for on Day One.