Buying the base game plus Chapter I separately is seven bucks cheaper than the royal edition?

The royal edition is currently on sale for $59.99. The base game is on sale for $24.99 and the Chapter I collection is on sale for $27.76. Together, the base game and Chapter I are $52.75. Am I missing something? Is there a reason why buying them separately is over $7 cheaper than the royal edition? It seems right now like there’s no reason to buy the royal edition instead of the base game plus Chapter I.