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.
https://news.ycombinator.com/item?id=32609732
That said, care to expand on the other reasons?
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.
https://factsanddetails.com/china/cat2/4sub9/entry-5471.html
https://history.stackexchange.com/questions/2012/did-the-chi...
Britain was a part of the Roman Empire for a long time. The lack of industrialization goes much deeper than river flow.