Lots of people do poorly in whiteboard situations. As an employer, you may assert that you don't want any of them, fine. But I don't see the problem in giving people the option of using an alternative testing process.
This isn't "an alternative testing process" as such.
> To solve the problem of interview anxiety, we're adding a second track to our interview process at Triplebyte. Applicants, if they choose, will be able go through our process by completing programming projects on their own time.
> The project-based track will require a larger time commitment (and we expect lots of people to stick with the standard track for this reason).