Oh, I don't disagree with you. Not one bit. There's a reason that swords are considered archaic weaponry and knives are considered tools for the kitchen and for utility in the trades. It doesn't make them any less deadly, but they're nowhere near as efficient as guns.
The whole reason that militaries moved to guns was precisely because they could train much larger numbers of people to be effective in war in far less time than it took to train them in archery. Swords really were more of an officer's weapon, but regardless, training someone to a level where they could be effective in combat, even single combat, is a very lengthy process. With the average student, it takes about a year to get consistent quality cuts, half decent posture and guard, half decent footwork, and half decent distance management. You can achieve the same efficacy with a gun in less than a month. No footwork, and distance management isn't nearly as much of a factor.