This is true, but I'm fairly certain that the amps of available power are calculated on a 120v basis, a 10 actual-amp washing machine would use 20 accounting amps at maximum power.
The rating of a service (and by extension, the main breaker) is available at 240V. It's true that if all of your 200A load is consumed on a single leg, with zero amps consumed on the opposing leg, that you would only be able to consume 200A * 120V nominal or 24kW, but if the load is balanced, you can pull 200A @ 240V nominal or 48kW.
