It is not only the ability to lift a big fish, it is the ease and rhythm of jigging, especially when you are using heavy jigs. Top water reels like 18000SW and the fast Saltigas will soon either wear you out at their normal retrieve speed, or destroy your rhythm by your having to reel so slowly.
Try to stick to the rough guideline of a gear ratio under 5 for deep jigging and over 5 for top water.