Residential US electricity primarily uses center-tapped single phase transformers, with 240V between the two ends of the coil, and 120V from either end to the middle. The center tap is grounded and treated as a neutral for 120V loads from either "hot", and 240V loads run between the two "hots".
The advantage is that we get 240V power with 120V shocks (assuming you grab a hot wire while you are grounded). The disadvantage is exactly what the original post was about: if the neutral wire breaks, it can fry everything in your house, because your toaster is now in series with your lightbulbs between the hots.
The advantage is that we get 240V power with 120V shocks (assuming you grab a hot wire while you are grounded). The disadvantage is exactly what the original post was about: if the neutral wire breaks, it can fry everything in your house, because your toaster is now in series with your lightbulbs between the hots.