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If the flake is 10m long it weighs many tons, adding 75kg of climber in the same gravity direction is negligible. Putting a torque on the rock along the breaking line is a different story.

(probably more like 50kg for skinny zero % body fat climber types)

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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.

The problem is that the type of protection you would typically use for this situation are spring loaded camming devices. These consist of logarithmic spirals that expand when they are pulled. If you fall on one of those in a flake, you are essentially taking a car jack to it.

http://en.wikipedia.org/wiki/Spring-loaded_camming_device

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