Parent is probably referring to a long time ago in the 90s, which indeed was a problem: you could get a better rate for your dollars on the black market than officially. The Chinese government finally normalized their currency mid/late 90s and the black market disappeared; the gov then realized that to support exporters, they actually needed to keep their currency artificially less valuable than more valuable....

Source:

http://people.hofstra.edu/geotrans/eng/ch5en/conc5en/yuanusd...

RMB was trading 1-1 with the dollar in '81, and started getting real about it in '94.