Earlier quoted context omitted.
True but what magnitude? On the one hand, I'm always surprised by (say) how many thousands of gallons of beer could be produced by a victorian brewery but equally, we make a hell of a lot more now.
A large chunk of that is simply differences in population sizes. The current US population is likely larger than the global population in 1,000 CE. Further, children used to make up a larger chunk of the population exaggerating the differences. So, it was often possible to scale up production even more, but there where not enough customers to justify it.
Not that it mattered since production of everything was, by today's standards, a few orders of magnitude less efficient. It's often difficult to fully grasp how inefficient and slow everything was in pre-industrial times until you dig into the details.