This is a power variation exercise for the core. Golfers, boxers, hockey, baseball, and tennis athletes all have something in common - the demand to generate rotational power. This type of movement dominates the transverse plane, but definitely incorporates the frontal and sagittal planes as well. All depending on the sport or desired action, there will be movement in some planes versus stabilization in other planes.
I love this exercise because it demands cardiovascular fitness, muscular power, and muscular strength and endurance. The desired and targeted movement is coming from the upper body - thoracic, scapulae, and shoulder rotation. What is naked to the eye is the force that is being transmitted through the CORE. These muscles are helping to generate and stabilize the movement! We know this because you can see minor movement at my hips and knees, yes the movement may not be 'perfect' to some coaches.
The goal of this exercise was to keep my pelvis aligned forward and stabilized. Some might argue this specific exercise could reinforce upper body dominance, and counteract kinetic chain sequencing of movement. For instance golf and almost every other rotatory power movement should be driven from the ground up and sequenced, "let the legs/hips drive the movement". I would argue the hips and legs are STILL working hard in this exercise. They help generate and transmit rotatory force, and eccentrically slow and control the movement side-to-side. This is where a hybrid strength coach decides when and where this exercise is appropriate.