It's not like they can't trade in person or with an online escrow service.
Well there are a lot of cameras and police in China, but yeah the government probably realizes it better to regulate the exchanges (require identification) than force people to go to the underground economy.
There is a huge Shadow banking underground finance economy in China. China knows that in order to take its place as the new center of the financial world by 2033, it must liberalize its financial industry.
This ruling appears to be right in line with China achieving its goal.
http://armstrongeconomics.com/2013/11/15/chinas-reform-push-for-2020/
(click link above to see this image if it doesn't appear)
http://armstrongeconomics.com/2013/11/15/china-a-new-era/
http://armstrongeconomics.com/2013/11/23/china-the-dollar/
http://armstrongeconomics.com/wp-content/uploads/2011/02/armstrongeconomics-the-assent-of-china-the-new-face-of-china-1-25-2011.pdf