What they are saying is that for you to do multiview it needs to have enough processing power on the *client* side. And because many ***** TV devices don't have the processing power to do it, they do the multiscreen on the server side which means you can't customize it. This is where the server side power issue comes in because they are saying it's not currently possible for them to do every possible combination ahead of time.
IMO they should do some gatekeeping in the app that allows for client-side multiview if your device meets a certain hardware spec, but maybe at some point they will figure that out.