I think the recommended paper is a high quality cotton rag bond. I would imagine that lower quality paper could have abrasive dirt mixed in its' fibers. Also, the exposed ring of lubed paper on the loaded cartridge could collect dirt which would act as a lapping compound. For years, I used a wad of hornets nest material over my black powder in my flintlock rifle after I'd read that it would slightly increase velocity and protect the patch from burning. After a decade of that, I believe it may have contributed to a fairly sudden (and premature) loss of accuracy. I think mud is the binder for the hornet nest paper and it would of course be abrasive. You could actually feel that the sharp edges of the lands was gone in comparison to the replacement barrel. This was not just ramrod wear as shortening and recrowning did not help at all. Even so, this probably took upwards of a thousand shots to seriously affect accuracy.
I have several friends who shoot muzzle-loading "slug guns" that require the use of lubicated paper "cross patches". These guys usually figure that a barrel, so loaded, has a maximum accuracy life of approximately 500 shots. The offender is the clay that is used to "size" the paper in the patches.
