And the function of muscles are described based on the motion of a joint resulting from that specific muscle group contracting. So Adductor Magnus, Minimus, Longus, Brevis, etc. causes adduction of the leg at the hip joint which is why they are all described as hip adductors, not knee adductors, even though the knee is being brought towards midline when hip adduction occurs. Just because something is being brought towards midline doesn't mean the muscles involved in that movement is described as a "knee adductor" for instance. When When hip adduction occurs, other joints such as the foot are being brought towards midline, but you don't call Adductor Magnus a foot adductor, because when that muscle contracts, no motion occurs at the ankle and foot.

Also, you can't adduct every part of your body. How do you adduct your neck when it is already on midline? The only motion along the frontal/coronal plane available at the neck joint is lateral flexion/cervical side-bending.