People always had a previous culture, wich had its norms explanations of the world etc. , but it was essentialy made by people just like those of the day. It is easy to question something that you heard from other people (even if they say it was told by wichever god they follow), but when you are created and stand before your creator who tells you how you should act, and how thigs work, you propably don't give them a second tought just take them as is. This might slow down change, and development making a permanent system where nothing changes, because the gods said it is good the way it is. Of course you can say, that not every one have seen a god, but the effect of gods walking among people may very well be strong enough to last centuries. This can explains, that if Yiliakum was put into medieval times, several hundred years later they still dont have steam machines.
An other important point is that magic is a way more powerful tool than those medieval people had, wich again can slow down technical advances. In the history of magic it is well documented that you should only use it as the gods intended it to be used (glyphs), wich again suggests that the things are good the way the gods made them to be, and thats it.
