Quran did talk about leadership.
Overall the leaders in the past were Prophets, and overall the Prophets were Messengers.
God didn't say Mohammad is the seal of guides or leaders, but said he is seal of Prophets. All the wisdom of stating there is no Prophets after Mohammad, would apply, to saying there is no leaders and guides appointed by God after. Yet, that is not what we see in Quran.
Not only that, but we see emphasis on the leadership dimension and the authority dimension and kingship dimension and the obedience dimension and being the way dimension and being a navigator dimension and being the light of God dimension of the Prophets emphasized all in context of verses that Shiite hadiths interpret to be about Ahlulbayt. For example Ulil-Amr, family of the reminder, etc....
And we see this Wilayah aspect of the Rasool is emphasized through out Quran as well.
And we not only see emphasis on this, but emphasis that they come as chosen families.
And not only do we see emphasis on chosen families and chosen offspring, but we see emphasis on their exact number, mainly twelve Succeeding Navigators to the founder.
And not only do we see emphasis on the number, we see it argued universally to humanity, recalling the twelve months - recalling the moon and sun cycles, just as Noah recalled nature to show the inward kingdom and Tawheed.
There was a very clean way of God throughout history, but people are trying to make it ambiguous.
And Ulil-Amr are in context in negating the Taghut and Anti-chosen/annointed ones Authorities, context of reminding of the Authority of a chosen family in the past, and afterwards recalling the obedience owed to all Messengers.
And Quran shows when people demand proofs but don't have proofs of their own, it is the case that they want people to follow conjecture and blindness and rejecting clear insights and proofs.