Because you had separation between the two.
I really never did consider mixing the molten metals. I was so dead set of throwing dusts and ingots in someplace to where i actually believed alloying could only be done in a crucible.
I did at one point think that the smelter might be able to do alloying though. I checked for it with the molten product of an alloy but i never saw a “smelter” tab. In doing so i must have just skimmed over the mixer tab.
By the way, i haven’t actually acquired tungsten yet. I still need to do a lot of alloying but you know, i keep trying to figure out ways of improving my crucible setup. Not really thinking about the other machines that could do better things.