Mankind is only becoming more informed, and the nation's sub-100s can do nothing about it. In our children's lifetimes, scientists will have perfected cell regeneration at the molecular level, thereby practically ensuring super-extended lives. They will look on us with pity.
Nothing the Cleti do will set back this advancement - best to make hay while the sun shines.
Yeah, but how much was built in the 7th century? And while some technology was relatively advanced at points in the Middle Ages, an overwhelming amount of learning was lost.