Except they don't.
If you pack a snowball with a mitten and throw it, you are only delivering, at best, 80 percent of that snow to the back of your stupid sister's dumb head. Likewise with the next snowball, and the next, until what you're left with is a snow-encrusted flipper in place of a once useful, noble, purposeful hand. A mitten is to snow as a pimp is to hos; it always takes its cut. With a glove, you can wiggle fingers, stretch the hand or use your free digits to carefully wipe away the accumulation. With a mitten, the best you can do is dully wave your frost-encaged limbs and hope that the rescuers realize you are in need of help, and not just really stoked to see them.So what the hell are they for?
Keeping children safe from the dangers of fingers?
Babies. A baby with mittens on is a fine baby. Look at their moronic little hands. They are basically clubs. Sure, they manage the occasional grip, but that's like a cat getting one claw stuck in a blanket: It is an accident of the body that only serves to confuse and enrage them. A baby's hands do nothing but slap and paw at the things they want, because they do not understand there are ways to acquire necessities aside from hitting (kicking, for example). In short, mittens are fine for a baby because they have little to no effect on their dexterity, and in fact may beneficially limit their presumptuously grasping fingers.
What, were you gonna type a letter? You're a damn baby.
Another possible demographic for the mitten: Dolphins, or possibly Dolphin-men.
The mitten represents pure, unadulterated hydrodynamics. It is only logical to make the connection between mittens and the dolphin. The dolphin can swim quickly primarily because of its thick, paddle-like fins. Fins that look suspiciously like mittens. The argument that dolphins are the descendants of early humans who simply couldn't give up their mittens is a highly logical one, regardless of how many times the scientific community refuses to publish our papers.