I don't really understand why a computer is necessary at all, is the thing. I know that it's possible to use wifi network to send a signal between two devices. I have a sound board that works this way, and manages to communicate precise multichannel instructions directly over the network without an internet connection.
If I want to turn on a light switch, it seems like all I should need to send is the location of the light switch on the network and the on/off command. I know that there is not the computing power in the light switch itself to process much more than that.
Do these devices all connect to a remote server to switch on and off??