Seems that the powered toaster/rack was created to allow people to use Kemper as a guitar amp, into a guitar cab.
Quite the contrary. At the very beginning, it was created so people didn't have to drag amps and cabs with them to shows. Then the powered version catered to those people that play in venues that have cabs at the venue. It was a digital alternative to amps that could be sent directly to FOH, then fitted with the possibility of also integrating it into your existing amp/cab rig. But the very conception of the Kemper was as an alternative to amps and cabs, not as yet another one.
Edit: Also, what Wheresthedug said.