The root cause of progress is precision in memetic transfer of information. In the past, knowledge was lost due to oral spread of information. Generations could inherit information from the past by telling the stories from the past, and we invented sacred canonical text to prevent too much informational loss in the most important domain of morals and cooperation, but we didn't have reliable mechanisms to copy information from one generation to the next. First writing, then manual copying, then printing and ultimately, the atomization of symbolic representations of ideas (words, sentences) into moveable letters in a printing machine changed that. We were able to spread ideas reliably on a massive scale and preserve that information for generations, so each could iterate on each other in detail. Then the industrial revolution and boom, there's your hockeystick.