Presumably even a router can drop into a low power standby-like mode if it's not being used 'in anger'. I don't think the article says that devices have to actually be powered off.
I suppose it's an energy variation of "look after the pennies and the pounds will take care of themselves
", i.e. nibble away at all devices, even low consumption ones, and gradually total consumption will reduce, or not rise as fast.
We have more and more laws, and less and less enforcement