The advantages I've found are pretty simple. One, if I'm eating more during my bulk, I'm stronger in the gym and have more energy. this will result in more muscle due to heavier, harder workouts. Two, its easier to identify if your body is reacting to your diet and training. Its harder to see yourself gaining .1 pounds of muscle a week. And three, its easier to set goals when you are focusing solely on gaining size or
cutting fat. Quantitative goals are one of the main reasons I stick to my regimen.
All of these are based on
personal preference though. Once I hit my ideal size, I would definitely NOT be bulking and cutting to look a bit better for the beach, I'd use your method.