Ah, I forgot about the rennaisance, mostly because in italy it started way before the cutoff year. So the rennaisance should be fine.
Well, what I was more thinking of was Artistotle saying that the equator was so hot man would instantaneously combust, or that European scolars had figured out how each people in the known world had descended from Adam and Eve. With the new world, where you could be on the equator just fine, and there were people there who could not possible have swam all this way, these theories were definitely disproven.
How about a simpler reason df development is stuck: One just does not share the secrets of steel making with the human, period and you're not allowed to write about it either
EDIT: Sorry if I came across as arrogant, I just read a ton of academic books last year on the history of science, and they pointed at the discovery of the world shaking things up more than printing itself, print was only an accelerator. I may have been a bit eager to share that.
The Portuguese had already crossed the equator long before Europeans arrived in the New World. Adam and Eve were not an initial problem because initially they thought they had reached Asia and it was not a problem once they had mapped the place because then they would know about Alaska and would (correctly) have figured out that the 'Indians' crossed over from Asia. Adam and Eve were disproved by Geology and Biology while Aristotle's core ideas were never dependant upon any particular scientific fact being the case at all.
One of the mysteries of life is that, unlike Dwarf Fortress everyone does not advance at exactly the same rate from a starting point regardless of where they are. I tend to think that the answer probably lies either in ideological differences, there are certain ideas a society needs to advance further. However ideas that propagate change to the Status Quo clash with powerful material interests that benefit from that Status Quo, they are usually armed with two weapons, religious fundamentalism and narrow pragmatism.
The former suppresses 'progressive' ideas because ignorance of secular knowledge is seen as almost a virtue while narrow pragmatists take the Status Quo for granted and over-focus ideas related to mastery of particular skills, which then become redundant or less important as the world changes.
Dwarf Fortress universe problem is more the latter than the former. Dwarf Fortress creatures do make technological progress in that they go from personally being dabbling at something to being legendary but they show no real interest in sharing their skills unless those skills are military, instead it seems that yes they do hoard skills rather than sharing them.
The existence of printing however is kind of problematic in this model. Once printed books are available fortresses would wish to have their high master of X write down books on X so that others can learn how to be more skilled. Once this has happened however those books are now available to be bought by other fortresses, meaning that technological progress actually occurs. Of course given the narrow pragmatism they are still only going to improve production of a limited number of things to perfection, but everyone reading a book that makes them a legendary dwarf by yesterday's standards is still technological progress.
Also, how often does your fortress last a decade? The printing press was not the internet. Technology spread faster, but not fast, definitely not like it does today.
An experienced player's fortress could really last for centuries. An inexperienced player's fortress is lucky to see it's third year.