>>135974
Increases rate of force at the bottom of a rep to use momentum to complete it. Not enough dynamic forces in people's training, so bands are good I guess.
You can get the same and better training from throwing a weight in the same exercise you would use a band, or an explosive version of it. Front raises can be front raise throws, ab crunches can be slamming a medicine ball into the ground or a sledgehammer, push ups can be clap push ups, etc.