No true Scotsman fallacy. Also actually right wing dictators that didn't try stupid socialist experiments were generally quite popular such as Vlad Tepes, many other European kings, current king of the UAE, Hitler, Pinochet and Bolsonaro. (I know Bolsonaro is no a dictator but lefties say that) Stalin genuinely tried to make collective economics work even when he already had power and no reason to fuck it up. So either he TRULY believed in socialism or he just had such a hard on for control that he would try to centrally plan stuff. However, I have not heard about Stalin himself actually doing all the 5 year plans etc. so I don't think that is the case.