A top coat is beneficial because it:

A top coat serves several important functions in nail care, with sealing the enamel and providing extra shine being one of its primary benefits. When applied over nail polish, the top coat acts as a protective layer, locking in moisture and preventing the polish from chipping or fading. This sealing effect not only enhances the longevity of the manicure but also adds a glossy finish that enhances the overall appearance of the nails. The shine provided by the top coat gives the nails a polished and finished look, making them more visually appealing.

In contrast, while some top coats may slightly accelerate the drying time of polish, this is not their main purpose. Additionally, preventing peeling of natural nails can be a benefit, but it's more about protecting the polish rather than the natural nail itself. Enhancing the color of the polish can occur with certain formulations, but again, the dominant benefit of a top coat remains its sealing and shine-enhancing qualities.