Serious MC personal problems cannot be solved by adopting the MC Solution because the MC is blind to the problem, the solution, and for Change MCs both the problem and the solution. In order to get to the point where a MC has the option to change or remain steadfast, he must grow past the blinders or pressures that prevent him from recognizing both options open to him: the path he has always followed (represented by the MC Symptom and MC Response), and the path not chosen (represented by the MC Problem and MC Solution).
The IC embodies that alternative path, which is why the IC has influence/impact on the MC as the MC struggles with his personal problems. In a simple sense, when the MC and OS are in a horizontal (companion pair) relationship, their perspectives on the inequity at the heart of the story are more similar than not. Since conflict exists in that relative spatial relationship, the MC's personal problems are alike to the bigger issue and the MC's grows by learning to step away, step back, or just stop his bad behavior before he may seriously consider the IC's approach as a possible solution to his own problems.
Conversely, when the MC and OS are in a vertical (dependent pair) relationship, their perspectives on the inequity at the heart of the story are about as dissimilar as they can be. For this reason, the MC¹s growth requires him to step forward, step up, or just start doing what he knows should be done before he may seriously consider the IC's approach as a possible solution to his own problems. As the story unwinds over time, the relative positions and/or tensions move.
Melanie and I recognized these patterns once we created the Dramatica quad structure and mapped the story points onto the structure, both spatially and temporally. A storyform represents a process and a set of states. The state of the storyform pattern at the beginning of the story is different than at the end, and the comparison of the MC Resolve indicates the relative positions of those to states: Change or Steadfast. The MC growth represents the process that the MC goes through from the beginning state to the end state. I hope that sufficiently explains what it is and why we describe it the way we did.