Flitz has grit
"I don't think there's any "grit" rating for Flitz. It says "non-abrasive" on the bottle. All it does is turn a smooth finish into a mirror finish. "
I think all "polishing" compounds must have some level of grit in them to make any change to the metal surface. In Flitz's case, it may be very very fine, but it still has to be abrasive (at perhaps some microscopic level) to do anything.
Even water abrades granite over enough time.