Although in all honestly, it's much less of a problem. Only about 6% uses an iOS version before iOS 8 at the moment. (I'm one of 'm!)

Interestingly, by doing this developers have a harder time supporting me (iOS 6 and 7 on phone/tablet). The result is forgoing app updates and even new apps altogether that I can't download. This pushes me to upgrade, and keeps the iOS adoption rate quite high. Facilitating devs in supporting old iOS versions does the opposite. I'm not a fan of this but I can easily imagine the benefits for Apple.