No power is greater than the ability to see the future. Whether it’s the ability to determine if turning right or left will lead to a better outcome or foreseeing the death of friends and family, knowing what lies ahead often tips the scales of power heavily towards the diviner.
In fantasy literature divinations are often vague and described as prophecy. Rarely does any character get a clear picture of exactly how things are going to unfold. After all everyone has free will and actions can be unpredictable. Divination magic assumes that people will continue along the paths that they’re most likely to take.
The advantage that authors of fantasy literature have when they’re creating stories with divinations is that the author controls all aspects of the story. This is certainly not the case in D&D (or any RPG for that matter). The DM may design and set the framework for the story, but with up to six players making decisions on how things are going to play out it becomes next to impossible for the DM to predict what’s going to happen next with any certainty.