The horizontal pull is largely neglected in CrossFit-style training, and when neglected it creates a structural imbalance in the shoulder, which can lead to injuries. This is especially true when you consider the amount of overhead pulling found in CrossFit. Combine lots of overhead pulling with lots of sitting, which causes rhomboids and mid/low traps to not work properly, and you increase the likelihood of wrecking your shoulders. The single arm dumbbell row helps build upper back strength which helps stabilize the scapula.
