Can't say this was THE reason but one thing that struck me reading zubok's Collapse book, 1 biography of deng and isabella weber's "how china escaped shock therapy" was the totally deferential attitude of the soviet reform economist towards the western economists and their theories compared to the much more contested relations between chinese and western economists.
Zubok's book shows the soviet economists completely buying into everything the western economists told them. While weber relates a reccuring event where western economists would sit chinese economists down in conferences and dictate to them what they should do, the chinese economists would silently listen, write stuff in their notes and go home, the western economists would then go home believing they had fully convinced the chinese. Then the next day the chinese economists would show up to the conference and dispute the ideas they listened to the day before, which would frustrate the western economists.
There was just simply more debate in the chinese case, Deng did not have as much power as gorbachev so even though he was at diffetent points pro-shock therapy, cautious reformers like Shen Yun also had the clout to frustrate those efforts