This is an essential question to answer. There are several reasons why the statement of the problem is foundational to all studies. Let me give you a few reason why.
First, studies are usually based on some sort of problem. We can say that the very reason why a study exists is to study a problem and offer solutions. So, from this perspective, the problem is foundational.
Second, if a person forgets the nature of the problem, a subsequent study may completely miss the mark. This would be in many ways a waste of a study.
Third, if you study a problem very carefully, it will give you tremendous insight. In fact, most great studies are based on an insightful understanding of the problem. Moreover, a profound understanding of the problem, not only shows intelligence, but also is the first step toward a solution. If this is the case, then the statement of problem is foundational.