Hands are fragile, they were created to hold tools. Like a stone. Stones are for hitting, not your poor fragile hands.

If you use a stone, you can still play the piano or paint your favorite landscape afterwards.

If you look at how Gorillas kind of walk around on their fists, it definitely makes sense that there's some evolutionary benefit to the knuckle shape. It doesn't have to be related to hitting things either. It's easiest to support yourself with a straight wrist, like if you're holding a branch, vs putting your palm flat is a lot more stress on your wrist.

Kicking is our natural unarmed attack. Still a last resort compared to throwing rocks or whacking with sticks though. We evolved from ancestors who already used tools to defend themselves.

Drag has fingers that are just the right size to shove up a huge cloaca. Does this mean drag was created for the purpose of giving handjobs to dragons? Yes, yes it does. And drag is happy with drag's purpose.