Fadden said China doesn't respect its own rhetoric on international scientific cooperation.

"There's another principle involved here. In international relations it's called reciprocity — that if we allow them to do x, they should allow us to do x," he said.

"If you look into what the Chinese allow, I think you'll find that very few westerners are allowed to study at Chinese universities looking into those 10 or 15 categories I'm looking at."

This pretty much sums up all the reasons. Don't get me wrong, China have some of the brightest scientist and researcher in the world, simply because distribution is a thing. It's much easier to get real talented people in pretty much any thing given huge enough population and if you direct your resource properly. You can say that their reliance on those odd approach might have killed their own innovation, cause talented people are still people, they can give up or trying to survive in their own way when the env do not give their best support and chance to shine.