>>87597752If you want to come up with a plausible explanation, it's that defense and offense are always engaged in a constant arms race and at various points in history one will always surpass the other - e.g. a sword can't go through plate easily but musket balls can, etc.
So you need to find a period where ranged weaponry can't go through the armor being used at the time but melee weapons and maneuverability are superior and can, much more easily, and use that as the time period for your setting
