Like Adam said one of the positives of Fat Bar training is the reduced strain on the smaller joints, specifically medial elbow and wrist, thanks to the increased surface area in which the weight displaces through the palm of the hand.
Another is irradiation, by making the hands and the forearms work harder the surrounding musculature is able to contract harder.
For bodybuilding, use Fat Gripz like a mechanical dropset. They limit the weight you can curl so start the set with them on. Then when you reach failure strip them off and rep out.
So if you have trouble with your elbows while doing tricep work for example, try Fat Gripz if you have access to them.