I think that I may have "miss-spoke", a bit. The clay sizing in patch paper is, indeed, abrasive. But, then, so is just paper and cloth. Muzzle loading round ball target shooters very often find that their barrels will "shoot slick", after a fair amount of shooting. Then, larger balls and thinner patches, and/or patch lubes with less lubricity are often employed to re-establish optimal patch/bore friction levels.
I am not aware of anyone who has manipulated variables such as bullet size, bullet temper, paper patch thickness or composition, and/or patch lube in order to compensate for the inevitable bore wear that results from the use of paper patched bullets. For all I know, somebody has, however. Experimentation along such lines might be interesting.