The forces involved are considerably more than body weight in a lead fall (potentially tens of feet before you're caught; at one point in the article they menti

The forces involved are considerably more than body weight in a lead fall (potentially tens of feet before you're caught; at one point in the article they mention the possibility of a 70 foot fall). 10 kN (roughly equivalent to 1000kg static hanging load) is a typical rating for lead climbing protection gear, and the only reason the force is that low is because the rope stretches considerably, reducing the max force exerted at any given instance.