I remember the ads, but I think most people did not have a water line near the stove so maybe it was easier to install a hot water dispenser at the sink. The idea was an interesting throwback though. Solid fuel ranges often came with a water reservoir to have a source of heated water in the kitchen. Other times ranges had a water coil on the back of them to supply hot water for the house. Imagine if a house had one of these and a water connection behind it. Years later, after the range was long gone, new people would wonder what a water pipe was doing behind the range.