it makes it a lot easier
I never thought of it, but I can imagine... Sharpening a blade is also best done with a Whetstone lubricated with water during the process (Tho Whet has nothing to do with the water, "Hwett(an)" is Germanic and it means "to sharpen or point"). But water not only lubricates it also is a coolant. The edge of the blade stays cooler and harder. Cutting dry material causes friction needs more energy to cut it, heats the metal and a warm blade gets duller sooner making it even harder to cut.