To clarify, I don't think "Fizzbuzz" necessarily means "printing out Fizz on multiples of 3, Buzz on multiples of 5, etc." Fizzbuzz generally refers to a simple programming test to make sure candidates can actually write some amount of code.
TIL I'm a terrible programmer.
Whiteboards are for diagramming things more complicated than lines of code. [e.g. Interactions between several web services or paths of control across entire programs]
I've honestly just accepted that by the standards of many people's interviewing processes I'm a bad programmer. :)
Interviews are stressful. Keeping the candidate relaxed should be on the interviewer's mind.