Because companies around the world are now aware of the fact that Chinese government steals technologies. Also, Chinese government is too late trying to get talents back.
Most of the laowais (expats) that were in Guangzhou, that were in technology, have left in recent years. The only foreigners left are africans trying to eek out a living and English teachers who can't make it anywhere else. You can imagine the reasons why: poisonous air that will give you cancer, poisonous food that will give you cancer, dirty water that will give you cancer, horrendous traffic (and everyone driving around honking and disregarding rules), bad mannered locals (imagine jackhammering at 4am, spitting, elbowing, cutting in lines), censorship, foreigners getting arrested without a reason, expensive rent (compared to quality), no way to be connected to the western internet without VPN (and recently, VPN have been failing as well), no way to talk to families overseas. And this is in the top province in China. Imagine tier 88 or even tier 2 cities. (shudder)
There's no reason to be in China other than to make money, then get the hell out. And that seems to be even harder now with the economy stagnating and everyone blowing bubbles into the real estate.
Thank god I got out of China. Many already have.