The title aside, this essay is about why Middle Earth didn't have an industrial revolution. Unfortunately, it uses a model with a limiting assumption which it i

The title aside, this essay is about why Middle Earth didn't have an industrial revolution. Unfortunately, it uses a model with a limiting assumption which it ignores, the assumption being that a certain population level is also required. High-labour-cost, low-coal-cost is fine and might fit our world. However, to get people to spend years in R&D you need specialization and scale. Without the first you don't have R&D people. Without the second there's no profit or even much advantage to the new tech. To get both of these you, well, need people. A good number of people to support specialists which aren't part of the Nobility (or at least Nobles which are engaged in activities which weren't historically considered very Noble-like in nearly every society in our world), and a good number of people so that scale can generate a profit. Industrial revolution can't happen by itself in ultra-sparse societies as in the LOTR era. The author cites estimates which are an order of magnitude lower than 17th century England, and I'd go one order of magnitude lower still*. Now if he asked the question about Númenor that's a different matter... (Yes, it was destroyed, but there were populous colonies in Middle Earth which should have kept any tech?) * Judging by the level of hostility involved and very high internal coherence of the protagonist societies I suspect a more total mobilization than your typical feudal society where losing simply meant the peasants served a different lord.