There are hadiths that are authentic, and then there are hadiths that are Mutawatir. This hadith belongs to the latter category.
Perhaps you are not acquainted with this hadith, its narrators and its transmitters โ here is what the historical record shows.
Some Muslims do believe that this implied merely spiritual authority and not political leadership โ but the Prophet (s.a.w.w.) himself held no such division in his authority.
Acknowledging rank requires no divine command, no halting of 100,000 pilgrims, and no revelation of the verse of perfection. What happened at Ghadeer was of a different order entirely.