Also home kit devices connect to the Internet (and yes, sometimes via their own hubs like with hue, which is a different matter - hue bulbs talk over zigbee not wifi so a zigbee hub is required and the Apple TV cannot be used instead) to talk to your iOS devices, so why should a "home kit hub" be required in the middle? What does it add?
$10 to the stock price?
But seriously, my guess is that the devices use Apple TV so that they don't have to be individually configured. If you set up a smart device to connect to the Internet, you have to be able to program each device with your iCloud credentials so that you can talk to it from outside your home network (because they're not likely to tie this to "Back to My Mac" and wide area Bonjour).
To do that, in turn, would require more software on your computer (translated "yet another pane in iTunes") to be able to teach that device how to connect to your Wi-Fi network, perform manual network configuration if your network requires that, update its software every time Apple decides to change its server configuration or update the protocol specs, etc. That would be an absolute pain in the you-know-what.
By contrast, if you do all the hard stuff (global networking) with an Apple TV, the other devices can be dumb as a brick networking-wise, and they'll still "just work", because they can use peer-to-peer Wi-Fi to talk to the Apple TV, thus avoiding the need to use your infrastructure Wi-Fi network at all.
And the Apple TV, unlike all those screenless devices, has an actual built-in user interface for configuring its network connection, can update its own software whenever Apple changes the server configuration or updates the protocol specs, etc. More importantly, you only have to set up all that stuff once on one device, rather than individually configuring every device.
So this rumor makes a lot of sense. With that said, it would be better if other devices, including Macs and ABSes could serve the purpose, and it would be best if it worked more like Bonjour Sleep Proxy, where the lowest-power device on the network serves as the actual proxy (and where any device that can't be turned off or put to sleep counts as taking zero power).
Source?
What did you expect? The need of a MacPro? Something has to be Internet connected and allways on... ATV is the cheapest and least power consuming device Apple has.
No, it isn't. If you have an Airport Base Station, *that* consumes less power. Well, technically, it consumes a lot more power, but it also can't be shut down, which means it is going to consume much of that power whether it is doing work or not. That usually means that throwing work at it is likely to cause the lowest power
delta.
So on a network with an Apple ABS, the lowest power configuration would almost certainly involve using the ABS as the proxy (assuming it is connected by Ethernet to the outside world), because that saves you from most of the Wi-Fi power consumption on the ABS itself (idle Wi-Fi takes less power than active Wi-Fi), and it saves you from having the Apple TV powered up. Even if the ABS CPU is dramatically less efficient than the one in the Apple TV, it would be hard to imagine it drawing more power than powering up all that extra hardware would.
If the ABS is connected to the Internet via Wi-Fi, the Apple TV *might* draw less power, assuming it isn't connected through the ABS.
This, of course, all assumes that the Airport Base Station hardware is even capable of doing peer-to-peer Wi-Fi on its own. If not, then I suppose the entire discussion is moot, and the Apple TV will always be the lowest-power device unless you happen to have a Mac that is configured to never sleep.
TV -wireless-> Router acting as an extender (.2) -wired->Router(.1)-Wired->Internet
