Could it have been because of the introduction of the bayonet, particularly in "socket" form?
This question goes (well) beyond a related question. Until the introduction of a bayonet, musketeers (unless guarded by e.g. pikemen) were very vulnerable to attacks by men carrying blade weapons such as swords or spears. And they had little or no clear advantage over archers.
But the bayonet gave the musketeer a dual-purpose firearm AND blade weapon which might have tipped the balance. Was this in fact the case?
Did the bayonet make it possible for musketeers to successfully "charge" equal-sized formations of archers without blade weapons that had been weakened by musket fire?
Could a group of men armed only with bayonets sufficiently defend themselves against equal numbers of men armed with blade weapons or was it the firepower afforded by muskets that made the difference?