They're referring to the recovery partition. And while most of the time you're never going to need such a thing, when you're dealing with a device like the Surface it's going to come in very handy when you do.
I have never used a recovery partition successfully.
But for the average, non-technical user, I think you'd see a much higher incidence of needing a system re-image due to viruses, malware, spyware, etc.