Why does the page count have to be in multiples of 4?

Because the actual sheet of newspaper is double the width of the page size. When we fold it in half, we get 4 pages when you print on both sides. For example, a 11x14, 4 page newspaper is really a single sheet of 22x14 printed on both sides. Thus 8 pages is 2 sheets, 12 pages is 3 sheets, and 16 pages is 4 sheets of newsprint.