A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
None of his statemetns suggest that anyone should be a true generalist, but that people should not focus on a single field to the exclusion of even a basic understanding of the rest of human knowledge.
There comes a point where the breadth of human knowledge is so vast that's it's not possible to have even a basic understanding of it all; I believe we passed that point long ago. All men are necessarily ignorant about a great many things.
-Robert A. Heinlein