Governments woke up to the use of paypal as a means of circumventing national tax mechanisms. For instance, assume that you work freelance, get paid over paypal, and spend it on newegg. Your government does not know anything about these, so they cannot tax it.
So they force paypal to use credit card instead of your paypal balance for payments. Therefore the money becomes traceable in your country as well, in addition to being transparent to the government of Hong Kong.
That is at least what happens in Turkey. I am not sure about other countries, but that's a theory that works.