I was hunting multiple tiers of mobs and wound up with a bunch of some junk loot that had the same name, but they didn't stack together. I assumed that was because it was a T4 versus T6 sliver for example. Then if I got used to the price of it, and tried to sell another tier of it, I might get confused because the price was different (well if I were a new player I'd find that confusing) especially if there was nothing in the description/name that indicated why it should be different than another sliver in a different stack.