I'm a bit skeptical of the idea that a person who devotes their entire life to their occupation is a more desirable employee than the one with a balanced life. Maybe if you were doing something completely rote, but who devotes their life to that anyways? To be a productive developer, you should also know how to:

Schedule and prioritize your work to align with business goals Interact with non-technical users and domain experts and understand their problems and techniques Work productively with and integrate your work with the work from related fields, like DBAs, designers, artists, etc Work with a team of developers productively, including making your ideas heard without being intolerant or offensive

That's stuff you don't tend to get from doing side projects. Maybe if you turned a side project into a real business, or were a senior contributor on a large, long-lived open-source project, or something like that.

Come to think of it, I was more sympathetic to the article's idea at first, but writing this makes me reconsider whether just having passion for something that you have built is enough to base hiring decisions on.