You clearly don't understand what fragmentation is.
Fragmentation isn't one device superseding another in capabilities, or rendering the first one obsolete. Those are all normal parts of evolving technology. No one expects a Pentium II to be able to run Crysis. It's simply beyond the capabilities of the older hardware.
No, fragmentation is when you have two devices of the same generation that support a different set of features. For example, the Red model might support features A and B, and the Blue model might contain features B and C. Want to make an app that requires features A and C? Tough luck!
You can call a "feature" hardware buttons, software support, or even whether a particular carrier has locked out a certain capability or not - but either way, this is a real problem that Android has that iPhone doesn't. Is Android better or worse than iOS? Debatable. But iOS isn't fragmented, and that's a point in its column.