Do you mean the original Fallout games by Black Isle (as in Fallout 1 and Fallout 2), or after Bethesda Studios took over the franchise? Most fans of the original series do not consider anything made after acquisition of the intelecual property canonical.
Not to get off-topic, but 95+% of people who have played a "Fallout" title have not played the original 2 Fallout games, so the opinions of this tiny group of "fans" doesn't mean much.
As I've said before, I think industrialization was caused by a mix of advances in labor, finance, and agriculture. The fact that Europe spent centuries in fierce competition among small states accelerated these advances. It should be noted that despite the high view many have towards the Roman Empire compared to the Middle Ages, there were very few technological advancements in the classical Roman Empire's 1000+ years of existence. Most of the Empire's achievements came from the availability of millions of slaves. Medieval Europe, however, largely abolished slavery and saw a huge advancement in the development of bridges, watermills, and windmills, not to mention architecture, scholarship, seafaring, etc. Therefore, keeping a large empire around would probably do a good job of stifling development and industrialization, maybe indefinitely.