There's a big literature on this in Chinese history -- many arguments concentrate on economics and labor specifically (to crudely sum it up, there was always lots of cheap labor available, and little incentive to invest the capital to develop and build expensive machinery so as to replace it). There are cultural and intellectual arguments too.
But this piece is totally wrongheaded in that it supposes that South China is China. For most of Chinese history, North China has been politically, socially, and culturally dominant (and not infrequently economically dominant too). It's too cold and arid to grow rice, and thus grows wheat and other grains. (This is why the cuisine is dominated by bready dumplings, e.g. mantou) Some of the author's arguments about rivers could apply to the Huang He (the Yellow River), too, but it has historically been much more central to Chinese civilization than the Yangzi ("Yangtze", or Chang Jiang - lit. "long river").
Chinese rivers typically have too large variation in water flow which makes the river poorly suited for year round usage for transportation as well as for water wheels. Chines water management has through history been all about protecting against floods and for irrigation.
Europe with more even waterflow has been much better suited for mills. You can see this in Europe itself. Italy never got as large number of mills as Britain as the rivers flowing into Northern Italy have too large variation in water flow. That is part of the reason Romans could never utilize waterwheels to a great extent.
I said in another HN thread that the Romans didnt innovate in energy. Someone replied that they did. Looks like you put a definite coda to that-- the Romans too were let down by their geography.
Continuing in this vein, rudimentary steam engines were known in both the Roman and Song eras, but the state of metallurgy is said to have held back adoption.
However the seats of power are more centered around Beijing in the south, where not much rice grows (though today you can find some rice farming in the area).
But this piece is totally wrongheaded in that it supposes that South China is China. For most of Chinese history, North China has been politically, socially, and culturally dominant (and not infrequently economically dominant too). It's too cold and arid to grow rice, and thus grows wheat and other grains. (This is why the cuisine is dominated by bready dumplings, e.g. mantou) Some of the author's arguments about rivers could apply to the Huang He (the Yellow River), too, but it has historically been much more central to Chinese civilization than the Yangzi ("Yangtze", or Chang Jiang - lit. "long river").