The problem with that theory is that China is not some primitive savage culture that has no idea how to "copy" Facebook (like savages who "copied" runways very poorly).
Chinese could easily copy Facebook and call it something else but with built-in restrictions that they're looking for. They take our tech and perfect it for their culture. That's not identical to a guy in a hut with a wooden walkie-talkie. Sorry.
The only difference would be is that it's a closed network. Doesn't mean it's "less" or "primitive" or "savage" when compared to Facebook. Just different.
The point is that china has it's own sites that are more popular than FB, WhatsApp, eBay etc, in a large part because they are more appropriate to local norms. This doesn't imply some sort of China-exceptionalism; Blackberry was huge in Indonesia and Orkut in Brazil.
They'd like to have some of the magic fecundity of the Valley too -- and why not? Though copying the overt structure doesn't get you there -- many many many have tried, including many in the USA (https://en.wikipedia.org/wiki/List_of_places_with_%22Silicon...). Hell, there are many studies and theories of how the Valley got to be where it is, with no consensus. I have commented further down in this thread on some unique or highly unusual factors that make it so effective (for me) right now but I have no solid theories of how it got to have the magic mix it does.
China policies are very protectionist so you cannot say if those companies would be successful in a 'open' environment. Their competition is just blocked there.
Echoes of cargo cult science[1].
[1] https://en.wikipedia.org/wiki/Cargo_cult_science