One thing that's always sort of confused me as vaguely propoganda when it occasionally comes up is that states that fought for their independence and had military-enforced sovereignty for several years are still counted as having uninterrupted US American statehood from the late 1700s onward despite the aforementioned time period. I understand that the constitution lacks a "leaving the union clause" but Big Gun Diplomacy effectively trumps a lack of specific clauses.

Is this a ~100% accepted concept or is there not any argument had over counting, say, South Carolina as being 225 years in the union rather than 229?