I don't believe anyone reading this will seriously argue that increased population drove the computer age. In fact, there is some argument to be made that the computer age has had the effect of reducing population.
As to the medieval age, the author might rethink his premise if he reflects on the Black Death which depopulated much of the known world, especially Europe, resulting in many positive developments such as increase in wages and standard of living of peasants because their labor had become scarce and demanded better remuneration. The Black death reduced population yet delivered an "advance in human history."
Wars for conquest of land and imperialism in general were often driven by the belief that growing populations needed to feed themselves from their neighbors bounty. Native Americans might argue that not only good things come from population growth. In the modern age we can cite urban sprawl as the negative consequence of population growth.
Too many assertions in this article are blandly made without proof. We shall see whether we need all these workers in the age of robots and artificial intelligence to produce goods and services. We shall see in an age of advanced medical science and wonderful new inventions whether we need more consumers or whether consumers will simply consume more goods and services and, for example, health care. Maybe we will just live better enslaving robots in a wonderful new age of artificial intelligence and marvelous materials.
This trope of Peter Zaihan in which everything turns on population might have some merit but have a care, the Chinese are learning all about the unintended consequences of trying to shape demography by government fiat.
Let God do it.
