Punching to the throat...well maybe a hard enough knife or ridge hand. It's easy enough to displace the adams apple or target either of the corotid arteries, both would affect breathing if damaged. Punches make the accuracy of the impact off, plus the neck is only so big, and the neck itself is rarely trained so most people just have a very little amount of muscle to pad the impact...leaving it #2. on the most vulnerable area list. In short; yes I would think you can kill someone if you hit them properly and hard enough...but the chances of doing this intentionally probably is less than the accident rate. So with that said, be careful.