Decent enough analogy.Overly-simplistic analogy: Imagine wiring a switch in parallel with a dimmer, just in case the dimmer goes bad, and you really, really need the light right now.
Ability to send full voltage and current to a motor to bump it past a jam or to keep a machine running that isn't really dependent upon a slower speed, in a case where a drive fails, there are other reasons, but these two come to mind, when I was looking for a drive, I read about this.