The original question... can punching someone in the throat kill them? The simple answer is YES... the complicated answer is all the tripe that's been put out so far.
Clearly the brachial plexus is located at the neck, along with the vagus nerve and other primary hitting points in the body's critical systems. Simply striking the wrong location along the lymph system can cause serious damage, not to mention the vagus nerve which is attached to every major organ in the body. As a self defense, it's a good method to be standing in front of a jury later.
Blunt force trauma to the trachea can cause swelling and shut off the air supply to the body, which is certain death. As a CPR instructor, I teach it's the loss of air that kills most people rather than their heart stopping... that happens as a result of the latter in most cases, which is why aligning the trachea to keep it open is so important in teaching CPR.
The last point, is simply force application to the spinal support of the neck. Punches and kicks to this area can cause the spinal cord to snap like a twig, and even if the person is lucky enough to survive, they are parapelegic or quadrapeligic from the loss of nerve connection lost from the disconnection of the spinal cord.
Those idiots that stand and let themselves be knocked out with pressure point attacks to the vagus nerve are asking to have major organ damage somewhere down the road, because there's a difference in resucitation and repair. While these "martial arts masters" can touch the points in the neck that attach to the vagus nerve and cause a knockout, it requires much more than resucitation to repair the damage to the major organs affected by such attacks. The Chinese acupuncturists consider many of these points "forbidden" because they require specialized treatment, sometimes for years, to repair damage to organs caused by hits on the vagus nerve.
If you need a more "modern medicine" reason for not striking the neck, remember that heart surgeons do not want to work around the vagus nerve because they cannot respond quickly enough in many cases to stop a complete body shutdown when it is touched. If you want to be "macho and dead", playing around with the brachial plexus and/or the vagus nerve in the neck is a good way to get there.
My 44 years in the martial arts say "Don't do it... its a trap".