There is something to be said for this point of view, but it is not one that is unquestionably accurate.
We can say that the emergence of the USSR was the most important consequence of the war because the USSR ended up being so important to the Cold War that dominated the second half of the 20th century. However, we could also argue that Hitler and WWII were the most important consequences of WWI. Hitler came out of WWI because it was German anger over the Treaty of Versailles that helped him come to power. His emergence led to the Holocaust and to WWII, two of the most important events of the 20th century. Therefore, we could just as well argue that the emergence of Hitler was the most important consequence of WWI.