They don't but they do give a false sense of extra "show" in what is largely a very boring routine.
I understand why they use them but they don't atall solve the problem that they are used for.
Bodybuilding routines are just not very interesting.
The reason bodybuilding routines are boring today is largely because of 2 things...
1. Most guys can't pose to save their lives - and dancing, robots, pop and locks isn't posing.
2. The shows are setup all wrong. They are too long, too much talking and sponsor crap, guys outside the top 15 get to pose when they shouldn't be allowed to (sorry but people don't care about the also rans) and the routines themselves are too long - half of which is the guys stomping up and down the stage demanding applause.
Compare a classic routine like this to Kamali and co and tell me which is more entertaining...