> That's partly true, partly circular.

I don't think there is anything "partly" about it being true. A moved-from object is expected to remain valid and preserve class invariants. If you wrote a class whose objects fails to remain valid after being moved,you wrote bugs into your code.

> Because moves work this way, it's harder to make a class that doesn't have empty states, so I don't design my class to avoid empty states, so the destructor has to handle them.

You are not required to implement an empty state. You are only required to write your classes so that after moving an object it remains valid. You are free to specify what this means to your classes, and can be anything from leaving the object as if it was default initialized or have literally a member variable such as bool moved. It's up to you. In C++'s perspective as long as your moved-from object can be safely destroyed them it's all good. Anything else is the behavior you chose to have, and bugs you introduced.