I second that; the blue dollar market existed many, many years before the cepo started in 2011. Mostly because anyone, but especially rich people, don't want to draw attention from AFIP, and every operation made at an official exchange agency has always been registered. Before the cepo, the spread between the official and the blue exchange rates was roughly 5-8%, but it was worth going to a cueva if you didn't want AFIP snooping around your finances.