Years ago I would look at a traditional slipjoint and it if didn't have brass liners, I thought it of inferior quality. Then Vic SAKs entered my world and they obviously don't have brass anything.... So, now I really don't care, but when I look at a slippie and see the brass liners, it makes me smile. I suspect it was used because it "was" cheap and easy to work with. Now brass is more expensive (at least it is at the scrap yard). I don't care for it on exterior parts as I don't care for the patina although I do nothing to stop it from forming.