Whiteboarding is a waste of time in my opinion. The problems are recycled anyway (reverse singly linked list, needle in haystack search, etc). It doesn’t give you a useful signal about the person’s coding ability when they can just do rote memorization on a toy problem.
I try to ask a simple question that pretty much any half decent developer should be able to solve quickly. Then we have a conversation about it and discuss why they did it, possible problems, how they'd handle new requirements, etc. It's more important to me that they can speak intelligently and collaboratively than memorize a bunch of puzzles. It is tough to determine if a candidate will be a good fit in the hour they give us.
For pure algo Q I would agree, but being able to use a white board to sketch out solutions to wider problems can be usefull - remember some people are more visually biased and may find visual aids like this usefull.
There are way too many problems to perform rote memorization.
Maybe that's the approach one takes when practicing, but hopefully they are seeing the pattern and learning algorithms to apply to solve each class of problem - or they already have learned that through their career, and such problems are just practice & exercise.
It's not about whether you can solve it, it's about how you solve it. But unfortunately, both interviewers and candidates focus too much on the former.
