It’s used for additional protection for your knuckles, while also allowing a full range of motion, regardless of what sport or activity you’re doing. Right now, place your non-dominant hand over one knuckle on a dominant finger, and try to bend the entire finger (keeping it mostly straight). Now, remove your hand and bend that finger. You’ll notice it’s two or three times easier. Now imagine having padding on your knuckles, prohibiting movement.\r