You still need to connect the power cord and connect to ethernet or wifi (end regardless of whether it is a cloud device or self-hosted device you can configure wifi from your smartphone like the chromecast).
A smart-home-controller is a physical device. You buy it, you provide power and connect ethernet and configure wifi. Now, either the controller relies on the cloud or it doesn't.
If it is completely reliant on the cloud you will have to muck about with registering, if it is completely self-hosted you don't. Simple as that.
EDITED REMOVING A REVERIE TO MY PROFILE, my apologies, often carried away when I'm enjoying the topics here, it's not my wish to spoil the flow as I almost did.
This said, I will surely be delighted to hear from anyone regarding my rather wistful wishes, to which I applied months of health enforced downtime last year. I still think the qualified opportunity isn't a total wash and would be willing to invest in a no tears no recriminations study, later in the year.
About the necessity of a WAN and firmware etc updating your home automation system: are we not in cities now at sufficient density where peer to peer hops in a as hoc network, has become a technical possibility that maybe lacks a sufficient motivation?
You are completely correct. But 99% of people don't know / can't be bothered to host their own. Googlezonbook will create a near frictionless experience and suddenly you'll need an internet connection to open your front door.