I've never run into that either, and I've read hundreds of Kindle books. My guess is the publisher didn't know enough about what s/he was doing to properly set the number of devices. As clueless to eBooks as some publishers have proven themselves, they might not even know what "number of devices" means.

Also, Gizmodo is often questionable in the material they present. For example, that article has an image of a library of Kindle books on some device and by showing those books one might get the impression that none of them can be viewed on multiple devices. The Steve Jobs book can be as I have it on multiple devices now.