When I started reloading in the 60's cleaning brass was almost unheard of. It was kind of the hallmark of a reloader that his brass was not shiney new.
Besides, I had the NEW WONDER DIES, the Lyman All-american Carbide dies with the gold top on the sizer die!!! They, and everyone else who sold those new dies, advertised that you didn't even have to wipe off the cases anymore because the carbide ring would burnish them clean. In fact, a couple of years ago the instructions to the RCBS carbide dies still said the same thing.
I do use a tumbler and get them real shiney now, but I don't think there is any way you could ever wear out a carbide die by running dirty cases through it, nor imbed something in the carbide and scratch a case.
Just my opinion, and everyone gets to do what they want to.
Education teaches you the rules, experience teaches you the exceptions (Plagiarized from Claude Clay)