No – an eight-inch blade will work on a 10-inch saw. The reason to use an eight-inch blade is that grooves rarely need to be more than approximately 1.5 inches deep, which an eight-inch blade set will provide. At the same time, increasing the diameter of the blade from eight inches to 10 inches will dramatically increase the weight of the blade, which means you would need a significantly more powerful saw. Dado blades typically are made in eight-inch diameters for this reason.