You're espousing a false dichotomy. The options in evaluating a candidate aren't merely "give them whiteboard coding problems" or "examine their side projects". Give them a take-home assignment. Give them an in-person assignment where they have several hours to complete a smallish design-and-build task. There are a lot more options, and I'm getting tired of people claiming they don't know how to evaluate technical candidates when it seems like people are just saying "whiteboarding is a bad test" and throwing up their hands and giving up.
Sure, you can use side projects to complement other data, but if you're relying on it as the primary measure of a candidate's programming skill, you're doing it wrong.
Sure, you can use side projects to complement other data, but if you're relying on it as the primary measure of a candidate's programming skill, you're doing it wrong.