That's on the 5.7x28. Those cases have a coating on them that you don't want to remove. It assists with both loading and extraction. So scuffing the brass scuffs the coating which can impact the function. That's bad.
With any other brass, that doesn't matter. Clean matters. I like the shiny, which is why I wet tumble now, but clean and smooth is what's important.
Peace favor your sword,
Kirk