One key reason I suspect is that you haven't been able to get SSDs in the cloud so their scaling up approach would be more difficult. Having your own servers me

One key reason I suspect is that you haven't been able to get SSDs in the cloud so their scaling up approach would be more difficult. Having your own servers means you can "NewEgg your way out of it" (http://news.ycombinator.com/item?id=3243133 http://news.ycombinator.com/item?id=3243133 :-).