I personally find whiteboarding / diagram drawing very irritating, for the same issue as most physics exercise: given a complex problem and you have to discard 95% of the problem to come up with a result that the teacher might thought.

The same with diagram drawing, 10 boxes and arrows, but missing most aspects of the architecture that actually matter. As a hiring manager I much more prefer to talk through the problem to see if the candidate can ask the right questions, thinks about NFRs, can suggest alternative solutions in light of new information.