My opinion (I'm not sure if it's right, but it makes sense and I've seen it happen) is that given that they're the only types which are both process and negative, they're the best suited towards painstakingly keeping in check potential errors, and improving a given process by means of elimination. OTOH a synergistic would improve a process by adding components, which doesn't necessarily work better (that's where negative-result-static should intervene and shed away useless fuss).