Yes, they can help immensely, but only if you are a smart training BB. Most of the powerlifter's do 4-5 excercises TOTAL per workout. Many bodybuilders do 4-5 per bodypart. If you introduce bands/chains to training like that you will just be beating yourself down.
If you on the other hand are a smart trainer, they will help add muscle and lots of pounds to the bar if used correctly.
Iron Addict