If to speak more globally, why China prohibits ?
There is such a thing in the economy as the outflow of capital. If large investors withdraw from the yuan country, the country will experience an outflow of investment outside the country. In the Communist society of China, the main prerogative is the development of the economy of the country, not its neighbors. For this reason there are disagreements in the power. Some believe that it will be better, and the party believes that it is not right. If we talk about my attitude, Let me give you an example.
So Look, I'm a collective farmer, raising Pets. It's time for me to sell my cows. I am looking for the highest markets, where the price is the most favorable for me. I found in another country, 100km from me a very favorable price. I go to sell my fresh meat, and they say to me: "Farmer, where are you going? you in our country only should sell!"And in our country it is not so profitable. Low price....
here's an example of the Chinese economy...