That's not the only alternative though. Why not use a more humane interview process involving conversation about previous work, ideas about the future, strengths and weaknesses?
> The total time spent is higher than most interview processes I think, which can be a struggle for some folks. But I do think it's the right tradeoff.
I don't agree but I'm glad you thought about it. I personally think making your interview process more inclusive allows you to get better candidates, as opposed to structuring the process in such a way to exclude those that have different priorities and life choices.
> Regarding why time taken is an important data point -- we found a strong correlation between people who were able to get good solutions working quickly and people who were able to effectively defend their solutions during the "GoldMine review" in their on-site interview.
Correlation doesn't equal causation though. I also want to point out that if you are expecting someone to "defend" themselves, that means you are on the offensive. Interviews don't need to be adversarial.
Edit: I do want to put in one good thing I got from your article to offset my rather negative responses. You mention that even if you reject a candidate you gave them the full code review and feedback about why you rejected them. The culture of secrecy surrounding rejections is something that needs to die, and I'm glad that although I think your process as a whole is unfair, you took the step to change that toxic part of our industry's interview culture.