Well yes. Many times.
But I'm not sure how that relates to the feasibility of punching punches out of the air.
I'm not saying it wouldn't hurt to have your arm punched while you are punching. I'm sure it would. It's not something I've ever experienced or seen happen though.
Punching at your opponent's punches??? Well, wouldn't most fighters
avoid that?
1. If you have boxing gloves on, you couldn't depend on significantly damaging your opponent's fist or arm, so better to focus on the main targets, right?
2. or, if you
don't have gloves on: 1. You might connect fist to fist or fist to elbow ...and that's risking breaking your hand.
3. Also, while you're targeting hands and arms which are small, fast targets, the other guy is targeting bigger, higher percentage targets close to the center of mass. That's why in WC we say "Don't chase hands!" Works for boxers and shooters too.
Now in self-defense oriented arts like
Eskrima where you might be holding a fist-load, palm-stick, a small metal flashlight, or even a cell phone, not to mention knives, etc. the equation changes completely.
If I have something like a hard, heavy
palm-stick, I would definitely try to hit my opponent's hands on the way in.