It would be meaningless, were it not for the context of the question it is answering. All of the electrical energy consumed is being turned in to heat in all those cases making it indeed possible to make a 100% efficient heater using electricity as was asked. The fact that that is orthogonal to the purpose of the machines is only relevant in as much as that's why they were chosen as illustrative examples, showing that even when you're not trying to, you end up making 100% efficient space heaters from electrical devices.