I like to make a mug rug to match the mug, especially when I'm giving it ( or a set) as a gift. Typically, that would be harder to do with a plate. Plus you can keep them in the end table drawer to grab as you need them - again , sort of hard to do with a plate. My smaller plate, that I might typically use to put cookies or small snacks on, doesn't have a flat area that would adequately stabilize a mug - it would have to sit on the slanty side and risk being knocked over, so a mug rug is much more secure - flat and not slippery. Need any more reasons?