There is a subtle difference between this and reductionism. Suppose your big problem is you are hungry. You could break this big problem into little problems in many different ways, e.g. [drive to McDonalds, get food], or [go to fridge, eat leftovers], etc.

Either way, you have solved your original problem, but you haven't reduced your original problem. Your original problem was not that you had to go to Mcdonalds, nor was it that you had to got o the fridge. Your original problem was that you were hungry, which is distinct from the solutions.