It’s not just the differences of language, history, and culture. It’s not just the (sometimes) questionable economic data, or the paucity of good Chinese academic research until very recent times.
Today’s China is [in a class by itself]. The country has grown so quickly that every decade or so there is a very new China. And so we cannot easily look to the past as a guide. In economic terms, China seven years ago is equally removed from China today as the United States about thirty-five years ago is removed from the United States today, putting recent cyclical factors aside.
You could say that China’s recent past is relatively thin in terms of information. For a more extreme example, how well would we understand an economy which went from zero to fully grown in the span of a week?