Some lifters have trouble hitting their backs, even with back exercises. Often, the biceps take over. The unilateral lat pulldown allows you to really focus on the back one side at a time.
Do not fully extend the arm at the top of the movement.
When you go all-in with one training philosophy - whether it's bodybuilding, powerlifting, or CrossFit - you set yourself up for a lifetime of repercussions, including lots of embarrassment.