If you leave to many parts in, you lead the audience to believe you are not really playing.
Why is it SO important to convince people that you're 'actually playing' a musical instrument. The very sounds coming out of an arranger keyboard would indicate to all but an idiot that you're not ('cause it's not possible to play drums, piano, horns, strings, bass, and guitar, at the same time - unless you're a very talented octopus). .