Another unique fictional aspect of the Game of Thrones world is that they have a well-documented and well-understood technology (magic) that just plain stopped

Another unique fictional aspect of the Game of Thrones world is that they have a well-documented and well-understood technology (magic) that just plain stopped working. Even things that you'd regard as chemistry e.g. wildfire stopped working when the dragons died. So you're looking at an environment in which normal scientific investigation might be unreliable. For that matter, if you've got dragons, who needs cannons?