Hm, maybe we call two different things a burnout. I had it twice, one ending in a visit to ER, the other one blasting a single song at max volume for 20h then crying and trying to quit my job.
I don't think the author actually had one, at least not by my definition of it.
That aside, my main cause of burnouts was working extremely hard on something and not finishing it, for a long time. Or always going after a moving target. Management and goal setting issue, really, and easy one to solve - break huge goals into subgoals, or even - don't have big goals at all.