I had a post upthread about people eliminating agency of foreign peoples and annexing their history into US history, and this is a great example. Nationalist China wasn't "lost" by anyone in the US, it was lost by the incompetent, brutal, and corrupt Chiang regime which managed to alienate vast swathes of the population and proved utterly unable to defeat the CCP. Chiang lost the Chinese Civil War (or rather Mao won it), not the US.
I agree with your statement that far to often the history of sovereign nations is co opted by U.S. history centric posters and my statement is a good example of this. However it does not make it wrong. General Marshall convinced General Chiang to not attack the Communists at Harbin and cut them off to the north of China. Had Marshall not given this poor advice to Chiang than Mao would have "won" the north of China but lost the rest of the nation. With the Soviets backing Mao with engineers and army railway corp members the war may well have continued but it would have been only in North China.
Chiang may well have been overthrown anyway but not by Mao. General Marshall scrapped the U.S. Exp-Imp Bank loan and halted the advance against Harbin. General Marshall was a "soldier of the world" and what he did in China in 1946 is significant to the history of the Chinese Civil War.