It seems to me that everyone has missed the point so far.
Collapsing before the finish line (like the girl in the "sportsmanship" flotrack video) is completely different from the all the girls collapsing just after the finish line.
The "mass hysteria" flopping after the finish is 100% mental. Nothing physical at all.
As a coach of high school kids this is one of the topics we address very early on in training. If you ever watch World Championship or Olympic races it is always the runners who finish way back in the pack who flop to the track after a race. 99% of the time the winner of the race looks amazingly fresh immediately after the race. Why is this? It is certainly not a matter of effort given, but being in control of managing your effort as a runner.
The winner of a race is usually the person who is able to remain calm and execute his/her race plan. The runners finishing in the back of the pack, chose to give up at some point in the race. At some point they decided that the effort required was too hard and they were not "able" to win or even execute their plan. In essence they lost control of their focus and their ability to regulate their effort. Additionally I don't doubt for a second that the runner goes into "excuse mode" at that point and a lot of the grandiose flopping is for theatrical/sympathy effect.
A good coach will teach young runners almost immediately to monitor their "effort" while running. Runners begin to learn actual effort from "perceived effort". "Perceived effort" allows for outside influences and distractions, while running on actual effort is 100% internal.
In any workout a good coach will walk the tightrope of maximizing the potential benefit of a given workout against setting a workout that is too hard resulting in the athlete failing. You don't wont to have failure in workouts that destroy confidence. So you push your athletes to the edge while teaching the athlete to simply gauge their own individual effort.
We don't allow young athletes to fall to the track during workouts until the last interval is completed and even then it is highly discouraged. We teach them to take control of their bodies by managing their effort. As the cliche goes "At the end of the day all you can do is give it your best shot". But you'd be amazed how many people are looking for ways out when things start to get tough. They don't know how to manage discomfort or suffering within themselves.
If you desire to race to the peak of your potential you must know how to manage your suffering. It must become second nature to you. Some actually become masochistic and fully embrace it, that's probably about the time you're ready to become great.
Those flopping mid to lat pack ladies at cross country races are not real runners. They have never been taught properly what it is to be a runner and how to manage their suffering/effort. I'm 100% convinced that they gave up at some point in the race because in their mind it was "too hard" and that is the result you see at the finish line.