This reminds me of something I heard archeologists discuss in the "Time Team" series I used to binge. I the UK, when the Roman Empire fell/collapsed, the populace didn't pick up and continue the Roman's tech (bath houses, currency, ...) but simply reverted to pre-roman tech of mud/wood/stone. They left the city to pick up farming again.
From what I've read, this is because the Romans didn't try to integrate the British people into Roman society, in contrast with many other societies they conquered. They kept the populace at an arm's length and lived in enclaves away from the hoi polloi, which meant that most people didn't really benefit that much from the "tech" until the Romans finally left; the monuments, buildings, and fortifications (including, famously, Hadrian's wall and the forum basilica) were used as quarries to extract building materials for what came after.
