I think it’s quite supportable, because that is what happened. What you offer is speculation, which while fun and interesting does not change history. Under the AOC, you had independant states which had their own governments, their own currencies, and in many cases maintained their own diplomatic ties with other nations.
Granted, the states in question could certainly gradually cede more and more power to Congress, somewhat similarly to how the EU is evolving today. Perhaps even the power to appoint a real executive. However, this did not happen, and a new system was invented instead.