> If more people meant more technology why didn't China/India bring out the industrial revolution?

This sounds like asking: 'Why did I get heads when I flipped a coin? Why didn’t I get tails?'. Innovation happened everywhere (examples: printing technologies developed way before in China than in Europe, Arab numerals and others)

> but actual tech disruption was way bigger in the late 19th century.

Not sure anybody can make an honest comparison. Sure, maybe that’s your opinion, but without some thorough analysis, I think it’s just an opinion.