If you imagine yourself working as a ranch hand in the 1890’s and carrying a pistol and rifle both and worrying about keeping ammo, it made a lot of sense to have the same caliber. Many of those guys packed a hand reloader and components. They were at times out for months away from home. Very dangerous work. Many did not return to home.
It is all about what you want to do with a gun. Range, size of game, weight of weapon and ammo, common reloading, etc.