Shouldn't an unrepresentable bad state not even have been proposed as a write tho? I mean the way I understand it, if something is trying to write a bad state somewhere, it is being represented somehow isn't it?

No, because you almost never have full data autonomy in corporate contexts. And the microservice arichtecures don't make this more robust either.

I.e. a transaction will have a matching transaction in another corporations/banks system, even if you don't have a distributed monolith unlike everyone else.