In 1932, American writer and editor John W. Campbell died in a car crash, so science fiction never got off the ground. Less people were interested in science, and technology did not advance as quickly. Post-WWII popular movements were anti-technological, and charismatic religion made a comeback. The Cold War is still ongoing in the current year of 2004.
Due to the extreme implausibility of the divergence point, Homeline scouts suspect a conspiracy by some other interdimensional faction.