I would say that folk hinders wrestlers in the lower weight classes more. Stylistically most sports diverge more in the lower weight classes just due to physics. At heavyweight, there are less scrambles and less freestyle exposures. At heavyweight, in folk style, you are much more likely to give up a TD if you take a bad shot than at the lower weights, so big boys are more strategic naturally. Snyder, Gable etc look very similar in freestyle and folk with the biggest difference being the pushout. It may be a better question to ask why we are successful at 57 kg than why we are unsuccessful at 65. That might just be it is a less competitive weight class, or something else.