Not only are they proven, they continue to prove, and will continue to prove in the future.
Some things just "are". *smile*
One has to bear in mind, folks often had only one knife, and therefore it was used for everything on the farm, ranch, property, including cleaning game. Game from birds, small game, to bigger game such as deer.
Some excellent examples have been shared before my post. My suggestion would be to find what fits your hand, and you feel you can comfortably carry.
Personally, I have a history with yellow handled, chrome vanadium, (CV) Case Peanut, Slimline Trapper, and Mini-Trapper. These being old favorites.
That is not to say I have not used YH/CV Sodbuster Jr, Stockman, and even the 32087 (bit bigger than a Peanut, with a clip main blade and pen smaller blade).
Recall the old adage:
"no tool is ever better than the user of said tool",
hence the suggestion to find what fits your hand, and what you can comfortably carry and use effectively.
The reality is, one never knows what they may encounter on any given day, and have to deal with, with the tools on person, so one would be wise to have tools they can use well.
Traditionals have a proven record, continue to prove, and I feel sure will continue to prove in the future.