We are talking about Germany at the end of WWI and not WWII. Jim Powells book is about how many of the conditions for WWII were laid down by the way that WWI ended, and may not have led to Hitler (and many other things) if we had let the land-war stalement (WWI) provide no clear or major winner. People today confuse Wilson's democratic hopes with the actual imperial ambitions of all the major European states involved in WWI - England and France included.
But your right about WW1, US never should have gotten involved!