A dishwasher is a machine, likely even more, but certainly not a tool.

It's an unreliable appliance. You load the dishes and close the lid, it's supposed to do the work of washing them, but the actual engineering inside is too sloppy, so you have a non-trivial amount of persistent stains you'd still wash by hand. You might correctly conclude that if this fraction is high enough, the machine is more of a hindrance than an aid.