The answer to that is a loud resounding NO!
The whole point of the gym ball is that it uses a lot more muscles than when you work on the floor. Balancing on the ball works means that you are particularly using your core muscles, so over time those muscles strengthen.
It also helps your balance overall, and you become more adept at fitness training.
If you know about mensfitness.co.uk, then you already know that they promote working with a Gym Ball - check out some of our Exercise Videos that show exercises they recommend.