This has been standard practice, and still is, to use powered abrasives to clean gasket surfaces, and not just scotch brite.
Even at shops that work on industrial equipment. It should have never been started, but those "FLAT RATE" mechanics are always looking for ways to go faster, oh and shops like fast as well. These two words conflict, "fast" and "quality".
There have been many very expensive parts messed up by using powered abrasives to clean "machined" gasket surfaces.
Lucky this doesn't happen in the aircraft world, nor does any of the hammer and chisel, pry bar mechanic-ing we see EVERYONE doing on youtube. The best part is when they drag a part across a concrete floor, or a metal top bench, or throw the parts around like the one highly praised transmission guy, and on and on.