Because Dish has said it. All the documentation that Dish provides does not show how to connect these other configurations. Anyone you talk to at Dish will tell you that it is not supported if you happen to figure out how to do it yourself. Like I said, you can certainly do it if you want... others have been doing it... but you need to keep in mind going into it that Dish isn't going to support any problems that arise from an unsupported configuration. I'm not making it up. Call Dish, escalate up to their highest support and see. There are surely reasons why it is not supported. We don't know what they have tested internally, what problems they might have found and decided it wasn't worth the headache of supporting for customer configurations. It isn't the first or last limit on supported configurations of Dish equipment, or any company with any equipment for that matter. Bottom line... Dish will activate the 8 receivers you are talking about... and Dish will even install them, in a non-interconnected supported way... and you can go behind them and re-connect to let everything see everything else apparently... but if you do have any problems that arise from that configuration, Dish is going to tell you "that's not supported" and you're on your own to figure out what's wrong OR you'll have to reconfigure to a supported installation to see if the problem persists yourself.