Why does The Verge use an iPhone 4 in some app reviews?

Obviously it's not that big of a deal, but I was just curious: why does The Verge use an iPhone 4 in certain reviews?

Here are some videos that do this: Sunrise hands-on Mailbox hands-on

One of the reasons the iPhone 5 is bigger is so that apps can take advantage of the bigger space, thus creating better apps. I'm sure someone at some point has an iPhone 5 in the Verge office, why don't they just used it for the reviews so that people can see the app at its full resolution / capacity?

Again, not saying that this is a big problem, just curious.