TJ – think you've gone off on a tangent there with your wiki link. (also dont believe what you read on wiki, most of the stuff is wrong)
Negligence and Duty of Care are two seperate things.
Negligence is where you did something you know you shouldn't have. Guide/lead somewhere you knew was dangerous.
Duty of care just means that you acted in a way that the average person would have done. If you guide/lead somebody down a route that you and many oher people have done in your peer group thats fine.
I can see why people leading rides are a bit cautious, but i hope that the organised rides dont stop. I've ridden some amazing stuff, and met some great people on these rides.
I'll lead one myself, when i can find a good route.