Successes of the League of Nations

Okay, so successes of the League of Nations were few and far between, but there where a few (lets not mention the long list of actions they let slide which resulted in tragedies that outweighed their minimal successes by far).
In 1935 the League of Nations supervised a vote in Saar in which the citizens decided whether they were to become a part of Germany or France, proving that issues such as these could be solved diplomatically rather than through war.
They did make treaties in attempt to enforce anti military build-up in Italy, which Italy accepted and then didn't follow. So again they remain persistent and tried to work with Italy, and when they continued to ignore the League sanctions were imposed including an arms embargo, an end to loans and credits, refusal of imports from Italy, and an embargo of exports to Italy for potential war material goods. So they did put their foot down eventually, they just had no way of enforcing their policies.   James G. McDonald, High Commissioner for Refugees for the League of Nations also helped many German Jews migrate to Palestine, but then he resigned when he decided that the League should directly challenge Hitler's policies, which didn't help the Jews any, but hey hindsight is 20/20 right?
All in all I think their biggest success was the whole idea and philosophy behind the League of Nations which eventually inspired the United Nations. My only question is why did it work now and not then? Was it the specific personalities of the time such as Hitler, Mussolini and Stalin that made it fail? Or was it people's inexperience and distrust of the ideas of Democracy?

Pgs 228-239

Throughout the reading I couldn't help but notice similarities in what was happening in many of the totalitarian European nations and what was or had happened in America. Hitler's belief that in the Aryan race was very similar to American views of the White Man's burden, Mussolini's corporate state in Italy was very similar to what FDR was doing in America during the depression, and Stalin's ideas of heroic propoganda and "socialist realism" was very similar to the idea of Uncle Sam and other American propoganda at the time. I'm by no means saying America was a communist or fascit or nazi nation, I was just thinking while I was reading this, America had the same economic issues and a lot of the similar philosophies as many of these totalitarian nations, what stopped us from becoming one of them? Was it just a matter of the right people getting into office? Or was it our already 'superior' stance as a world power? Was it something else?