There is absolutely fragmentation! What used to be one app is now three: Facebook (minus chat), Paper (with chat), and messages (only chat).
This time last year 2/3 of those apps did not exist. They have fragmented the user experience into entirely different apps. The concept you are mistaking for fragmentation seems to be the concept of duplication'. Right now all three apps do messaging and they will soon be reducing that number to two (Messages and Paper).
Not sure your math checks out…