In fact, all tourists were supposed to use them. It was a second, separate money circuit that was semi-convertible. The first circuit money (Cuban pesos) was not convertible. The intention was to keep your average Cuban from owning something convertible. The real effect was to put a premium on the second circuit coins and notes, proving the inferiority of the first circuit currency. China had a similar second currency in the seventies, but it consisted of banknotes only.
Peter