How do sugar granules affect cookie spreading during baking?

In the context of baking, the size of sugar granules plays a significant role in determining how a cookie spreads and expands in the oven.12

This effect is primarily driven by the competition for the limited water available in the dough. Because sugar dissolves slowly, it competes with the gluten of the flour for moisture. By influencing how quickly the sugar dissolves and interacts with other ingredients, the granule size directly impacts the final texture and the degree to which the cookie spreads during the baking process.12