Very interesting read. Not sure that if the same summer camp experiment was held now, with properly raised children, that the outcome would be quite the same. There might still be some competition, but I doubt it would come to nearly murder.
Your comment displays the very asymmetric bias the article is about: we're not like them. Our children are raised properly.
While I don't disagree with what you're saying, I do think that the general culture is a bit more tolerant of differences now than it was when the experiment was run.
I think no matter how well you raise a 10 or 11 year old, at that age they are still impressionable and subject to a lot of group-think and peer pressure.