Are you sure thats recent? Its been like that ever since I started programming for the iOS platform (3 years ago) and before its something you would hear about pretty consistently with each major iOS update.
I personally don't equate fragmentation with different screen resolutions/sizes/aspect ratios. An eco system should have a large swathe of options. One size does not fit all in this case.
The fragmentation I feel in iOS comes from its tedious way to deal with the different screen types.