Yeah... I'd ask an historian about that.
WWI was a dumb war for America. They joined, and then Europe felt that it was far more important to "punish" Germany than to do other stuff. America was the only Allied country to ignore/reject the signing of the Versailles Treaty, due to the fact that Europe completly ignored American Opinions on the treaty.(America actually took a less "offensive" stance than what Versailles Treaty wanted.)
Following this, with the Rise of Nzi Germany, the US didn't want to participate in
another war, after how disgusting the First one was. Sure, people such as Roosevelt believed that we needed to go to war, but the majority of people were Isolationist. Japan Changed that.
Then Russia decieded to NOT move it's troops back to Russia. Had it wanted, Russia could have pushed forward, but have the only WMD kinda helps keep things in check.
OBV, that's really short explanation since the factors leading to WWI were very, very complex for all sides, especially Germany.
I do find it funny that people do revisionist history. It's becoming, sadly, more prevelant. I saw it not long ago, a history topic I once read and studied when I was younger has been changed to something so...different...it's disgusting, really.