While that is a major issue, you are incorrect about the true destruction of States as being separate political entities being that. It was the Civil War and when it was decided you can't leave. Being a separate political entity directly implies self determination, and the most fundamental choice of all in that is whether to associate with the others in the first place. Every other choice a State makes as a member of a larger Union is downstream from the decision whether or not to take part in that Union to begin with. Once that decision, whether you take part in the Union, is taken from you, all other self-determining decisions downstream from that aren't really self determining anymore.

While that is a major issue, you are incorrect about the true destruction of States as being separate political entities being that. It was the Civil War and when it was decided you can't leave. Been a separate political entity directly implies self determination, and the most fundamental choice of all in that is whether to associate with the others in the first place. Ever other choice a State makes as a member of a larger Union is downstream from the decision whether or not to take part in that Union to begin with. Once that decision, whether you take part in the Union, is taken from you, all other self-determining decisions downstream from that aren't really self determining anymore.