Right, and some of us have a fine tradition of using extension cords as a way of powering some things during an outage with, eg, a portable generator buzzing away outside.

It's clunky and haphazard, but it can work well-enough for rare use.

But one of the big sells in the article for this device is that it can be used to buy power when it is cheap, and sell power when it is expensive (at least in markets that support that kind of operation). This can be good for the owner (who can make some money doing it), and also good for the grid (the price fluctuates when supply and demand aren't well-balanced, and this function helps to balance things).

That kind of functionality, on its own, can tend to require some real wiring changes and permitting.

(Or not. Electricity rules vary wildly around the world. They aren't even necessarily consistent within one nationality.)