All stains need a top coat. Think of stain as the color and top coat as the sealer and protectant.
The high urethane content of General Finishes Gel Stains results in a lustrous finish that tends to fool people into assuming no sealant is required. The beauty of Gel Stain comes from thick thick urethane which can carry a LOT of color to any surface, but that color must be sealed in with top coat. An added bonus of top coat is that it also protects the wood from drying out.
Think of stain as the color and top coat as the sealer and protectant.