The "Inciting Incident" is a nebulous term and therefore insufficient in matters of story structure and analysis. Some see it as the event that starts the story while others see it as the "Call to Adventure". Even Hero's Journey advocates find it less than useful:
The Inciting Incident is a confusing term and, in general, not very helpful. Within the context of the Hero's Journey, it could represent a few points of action…Perhaps the Inciting Incident is useful in [infantile] three, four or five act structures, but amidst the complex Hero's Journey, it is less useful.
Ignoring the ridiculous comparison between the Hero's Journey and other "infantile" understandings of narrative structure, one witnesses a lack of agreement over the function an Inciting Incident actually performs.
The Call to Adventure
From a Dramatica point-of-view, the Call to Adventure is simply the moment where the Main Character and Overall Story Throughlines meet for the first time. R2D2's delivery of Ben's message in Star Wars weaves in Luke's constant need to find ways to test himself against the larger world's concern of finding someone skilled enough to help fight the evil Empire. The revelation that brother Joe listed Lee (Casey Affleck) as guardian to son Patrick in Manchester by the Sea pits the empty black hole of wanting anything within Lee against the bigger picture concern of a dying man's wishes.
This functions as a sufficient definition of Inciting Incident--if it weren't for the fact that these stories don't start with those moments.
The First Story Driver
Instead of relying on amorphous "Inciting" moments, the Dramatica theory of story looks to the initial creation of the central inequity within the Overall Story Throughline. Dramatica refers to this initial event--whether it be an Action or a Decision--as the first Story Driver. This moment marks the dividing line between the world at peace and the world embroiled in conflict--the world that needs a story to make meaning of the efforts to resolve that conflict.
Death Vader's illegal boarding of Princess Leia's ship is the initial Story Driver of Star Wars. Sure, the Rebels and Empire were at odds before the story began, but it was an equitable conflict--like the Cold War between the US and Russia. His blatant display of hubris upsets that tender balance and motivates everyone to search out a way to fight back.
Joe's diagnosis—shown out of temporal sequence within the movie—is the initial Story Driver of Manchester by the Sea. Lee's personal problems start sometime later, yet it is this dire set of circumstances that forces Joe, his wife, his attorney, and his friends to begin the process of making key decisions in the planning of Patrick's future.
Diagnosing the Start of a Story
As you can see, knowing the identity of the Inciting Incident does little for an Author. While masquerading as the beginning of a story, this mixed-up charlatan confuses issues and mixes perspective in its attempt make things easier. Authors need to understand the difference between conflict as seen from the Main Character point-of-view and conflict as seen from the objective Overall Story point-of-view. A term like Inciting Incident blends the two, leading to all kinds of subjective misinterpretations of conflict.
The Main Character Throughline naturally collides with the Overall Story Throughline at some point within a narrative. Knowing when it does, or the nature of it, matters little to the actual meaning of a story.