I think that is the story from what Cliff said in his original post. Maybe not everybody, but "others" have fallen in the exact same location and they had advised the organizers on several occasions that this was a hazard.
Lets take Brian's example and say you went to his cottage and were walking on his dock and a huge nail dug into your foot, you fell and cut yourself and needed stitches and a hospital visit. It was so bad and became infected and you had to go home early and someone had to pick you up and drive you home. You missed work and had various other expenses. He's your friend so you say oh well, that's life, guess I wasn't watching where I was going, but you mention that he should fix that in case someone else gets hurt, and he just shrugs it off. Then you hear that since then, several others had the same thing happen to them and the injuries were just as bad or worse.
I'm not saying you would sue him, but those others certainly should have been made aware of the potential danger and it should have been fixed. They could sue as he knew it was dangerous (you could too but we're being nice here).
In my opinion it should have been fixed and nobody should have been allowed to enter that area until it was because of the known potential danger and liability.