Why do you think white boarding over the course of an several hours would be a better predictor of these traits than years of making very meaningful contributio

Why do you think white boarding over the course of an several hours would be a better predictor of these traits than years of making very meaningful contributions to software? It seems to me like creating and managing a repository of more than 4800 contributors is a much better signal of a candidates software engineering, communication, and human skills than a couple of people's opinion of a couple of hours of white boarding.