My guess: What screwed China was the Roman alphabet because China didn't use it. Then when the written word became important for the masses in the West and for progress in the West, China started falling behind.

The effect is still easy to see in Chinese culture, say, cooking: It's still strongly the case that Chinese cooking is essentially just not written down and, instead, is learned by apprenticeship. E.g., I have stacks of books on cooking -- US, French, Italian, German, and Chinese -- and far and away the worst written are the books on Chinese cooking. So, the books on American cooking I got from my family from, say, the 1930s, are very nicely done with times, temperatures, weights, and volumes, but the books on Chinese cooking have essentially no measurements at all. Then for explanations of the steps and details, again the Chinese books are far behind. Again, simply, Chinese cooking is so far nearly never actually written down in anything like what is common for thorough descriptions in countries that use the Roman alphabet.

Why the Roman alphabet? Because it's so darned easy to work with, and the Chinese little drawings severely throttle what that masses might do with reading and writing.