Sure, I never said fragmentation was the issue here, in fact that was the point I was making. Unless you're a developer it doesn't affect you.
I'm well aware Apple tends to provide updates longer than Google, though as +Konstantin Walter
pointed out, that's less of an issue for Android users. But my point was, if you buy a Nexus device and expect three years of OS updates it's your own fault, because the two year cycle has been known for a long time and is now official policy (2 years major OS updates, 3 years security patches). In short, there is no issue here.