Its not the friction that is wearing down the muzzles, but the microscopic grit that can be picked up by wooden, aluminum, carbon fiber, and brass cleaning rods, or arrows, that cuts the arrow rest, or the muzzle of the gun. Since muzzle guide are so inexpensive, and come in both brass, and a nylon synthetic material that is much easier to clean, and does not hold that microscopic grit, why not use them to protect the barrel?
That does not mean that someone with very good loading skills, well practiced, over years of shooting, cannot load his rifle with a wooden ramrod, and not experience any wear at the muzzle of his gun. As long as you load slow, careful, and act like the edge of the muzzle is a switch to a loud alarm and a painful electric shock that will punish you if you touch it, you can use an ordinary ramrod to load that gun for years without any sign of muzzle wear.
When I was very young, I watched an older shooter, with an original gun he inherited from his grandfather, loading his gun just that slowly. He was appreciably slower in loading the gun than the other shooters, often only firing one shot for every time they fired two! But his shots were in the ten ring, so I paid attention. When the line was closed to change targets, I got a chance to talk to him about his loading procedure.
What I have explained above is why he was loading so slowly. He showed me the muzzle of his gun, and it looked as sharp as the day it was made. Now, having tried this much later in life, You use your hand holding the muzzle of the gun to act as a muzzle protector, insuring that the ramrod is aligned straight, and will not touch the side of the muzzle at any time. It does take very slow movement to guide the rod down the barrel as you are seating the PRB.
I have gotten " lazy " since I bought a range rod of stainless steel with its nylon muzzle protector. Its easy to sipe the rod clean several times during a match, to keep grit and grease and soot off my hands, and wiping the muzzle protector with a solvent, and then a clean patch before it goes into storage is small work.