@Jackgiantkiller Offering traveling strangers beer is basically the true start of civilization. ;)
I agree that the visuals we have are mostly based on a later age. But gunpowder has little effect on the looks of it.
So for me, when I'm world-building it came mostly down to the following: Does the world make less sense because it lacks GP? Answer: No.
The same can usually not be said by in-game justifications beyond "just never happened". Different laws of physics, wizard's cabals, divine intervention - all logistically troublesome and beyond my usual desired power level (I use kitchen sinks, I don't build 'em).
Just my personal approach, though. Mileages do vary.