[lylecheatham]

They are pretty fundamentally slow because of the constraints from the melt pool. Because you are trying to locally melt the material (lots of energy) and then immediately solidify it, you pretty much have to use a melt pool under a certain size and go under a certain speed to avoid making a total mess of the part.

Also a significant amount of energy goes to waste as it gets dissipated by the material, and the powder feedstock is extremely expensive as it needs to be a certain size of round powder which is hard to manufacture.