The legitimacy of the Rightly Guided Caliphs, political conflict during their rule, and the special thirty-year description are related but separate issues. Recognizing ʿAlī’s rightful caliphate, interpreting some actions as competing ijtihād, and counting the period through al-Ḥasan lead to distinct conclusions.
Keeping these discussions separate prevents the mistaken inference that every historical dispute invalidates a caliphate or that every wrong decision represents doctrinal rebellion.