-Robert A. Heinlein
Robert Heinlein is a very interesting person and writes fascinating books. He also has lots of patently silly ideas, and this is one of them. Specialization is responsible for lifting humanity out of the small tribe hunter/gatherer stage to the modern age nearly by itself, and is one of the things that mostly strikingly separates us from all the other species that surround us. Though insects certainly do specialize, they do so into a fairly limited number of roles, often something like 5. Humans, by contrast, specialize into literally thousands or tens of thousands of roles in our modern society. I cannot diagnose a disease, repair a car, run an MRI machine, operate a welding machine or write C++ code, just to name a tiny fraction of the essential skills that people in our society possess. Certainly I could be trained to eventually do any of those things but the vast array of skills found within our society cannot be mastered by one, nor even a hundred individuals.
The greatest contribution of specialization, to my mind, is the increased capacity for development and innovation. While I could be trained to do simple engine repairs it would take a much of a lifetime for me to have enough experience to be able to give real, informed opinions on designing a better engine. If I need to master a dozen skills I simply cannot understand each well enough to make much contribution towards improving them, while someone who spends their whole life doing one thing can easily see the places that need improving. Not only that, but they have the capacity to understand how even very small effects will change complex systems. This understanding is mostly not obtained by real knowledge of how everything works at a physics level but rather just a manifestation of experience over many repeated trials. The best forward in hockey doesn't know exactly what he does to make the puck move a particular way but he knows the precise way he must move his body in order to maximize his chance of scoring - even if he couldn't possibly describe that process usefully to someone else.
Of course much of our specialization comes in seemingly useless things like scoring in hockey. Half a century ago there were great players who dominated professional sports, just like there is today, but those great players would be mediocre if placed directly into a modern game. They usually had to work other jobs to pay their way and did not have the practice time, training and equipment to maximize their specialty. As our society grows richer and richer we can support more and more specialists who produce virtually nothing of value beyond being even better at their specialty than people were in the past. I don't see any way in which hockey players generally being better actually helps anything - the old games were perfectly entertaining even though the players simply weren't as good. However, it is inevitable that as we become capable of supporting such specialists we *will* support such specialists as anyone who does hyper specialize quickly outstrips the generalists in skill and innovation.
The number of roles that people can specialist into and still be supported and useful is growing year by year, much faster than the population of the planet is increasing. It is to be expected that we will become even more divorced from nearly everything that everyone else does over time simply because there are so many different things to do. I wonder how long it will be until the number of roles and skills required becomes even greater than what the population and communication of our society can support.