I agree with you. Participatory design is not the same as testing a Hypothesis, which is what CD is about. The easiest way of thinking about it is what Henry Ford said "If had listened to my customers I would have bread faster horses". What Ford did was look at the Activities of his customers (need to go from a to b faster), and their needs and then came up with a Hypothesis which was the car.

He still researched the market, he still listened to his customers, but he did not use the customers solution, which is what Participatory design is about.