A rapid downshift can make the rear wheel resist the road speed as the engine is forced to spin faster. A slipper clutch allows a controlled amount of slip when back-torque becomes high.
That can reduce rear-wheel hop and make hurried downshifts calmer. An assist function uses clutch geometry to reduce lever effort under acceleration, which is why the two features are often advertised together.
The hardware is useful, but it is not permission to ignore smooth inputs. Matching road speed, gear and engine speed remains good practice on every motorcycle.
