Fusion rifles don't one shot outside of shotgun range unless you are really lucky. This means they cannot compete, and they don't have the charge time to compete with a primary at medium range specifically because they do not one shot. Seeing as they are designed for medium range, it is a problem that they can't be effective at this range (at least not the old ones since they were just nerfed). I will withhold my judgement on the nerf as a whole though until I see the current design for fusion rifles.