Although canned dry parmesan in a can is cheaper and easier, it is not better in any way when you are using it in a recipe. It can be used on spaghetti in a pinch, but not when making salad dressing. First of all, it is powdery and does not melt like shredded cheese. Also, it has a gritty texture, possibly from the sawdust additives they use to stop coagulation.