Earlier quoted context omitted.
You’re not looking at it radically enough. “How would a non-specialist survive in a specialized world?” is not the question the author seeks to answer. Rather, the question is “what would a non-specialized world look like?” and I think the answer is something resembling pre-agricultural society.
Wanted to call out that this would probably require most of us to never have existed. Specialization is more efficient at the macro level; this efficiency is why there are 7b humans instead of many fewer.
Increases in economic output, agricultural and industrial, make it possible for more people to survive. If further and further specialization lead to more and more efficiency with ever growing population, is there a point where we decide things have gotten worse? Or do we slide down the slippery slope into some hellish future dystopia with 700 trillion people, crammed into skyscrapers full of capsule apartments, subsisting on genetically engineered bio-protein sludge and pacified by neuro-electrical stimulation? Not far off from The Matrix.