When I lived in Waterloo, down the street was the meat shop of Rolf, a German fellow, licensed, in Germany, to cut meat AND make sausage. Two different trades, there. When he introduced that to me, it was when I asked for Braunschweiger, of which he was out, but he said I would probably like Mettwurst. He was right.
That was 50 years ago, and I still remember it.