What's astounding is that at least in this case simple arithmetic could have shown it was unsuitable - since 13,000 / 2,300 is just 5.6 pounds - a force any below-average middle schooler can obviously exert at least briefly (being well under 10% of their body weight and for reference the weight of less than two stacked 13-inch Macbook Pro notebooks -- which would weigh 6 pounds. A gallon of milk weighs 8.6 pounds.) It could have been expected that perhaps every one of those students would exert it continuously through the whole contest to say nothing of their maximum extra effort on top of it.
While 13,000 pounds is very strong - a full 6.5 tons - it sounds like a simple arithmetic check could have saved the disaster mentioned in the write-up. The lesson - or at least one lesson - is, never feel above a simple calculation.
Edit: also not all the students were competing at once. Still, even with only a few hundred it'd be too close for comfort. For a safety-critical thing like this you want a healthy margin.
It feels natural to do so, when standing on a ladder for example, but you can easily lose it.
I am not sure that works with tug of war ropes, though, as they, given the forces used, are too thick to allow for that zig-zaggy bend.
I certainly don't see it in photos on http://www.tug-of-war.org.uk/towtactics.htm
The last player on each end can safely wrap the rope around themselves if they like. The rope behind them is slack, so the only tension on the rope is the tension they put on it themselves. Where people get into trouble is when they are somewhere in the middle where there is (significant)tension being applied to their section of rope by people on either side.
Anyways, my school is one of the few left which still honors the tradition http://huskiesifc.org/the_site/?page_id=45
The fraternities train like hell for months, it's the real deal.
If you want to see one hell of a tug of war look up "NIU tugs" on youtube.
The really old pictures show it was traditional done over stream so the losers get soaked. Now it's done on dry ground but it's still just as serious. The ropes and other equipment we used likely dated back to the 60's or earlier. The rope was so huge...Maybe 5 inches... It was definitely made for boat anchors