I think the real problem is that you don't know whether it's a good analogy in your situation. You don't know whether you're lowering the anvil or just fraying the rope. It depends on a lot of hard-to-measure things about your whole geologic situation.

It makes sense to me, if you consider that a "damaged rope" is a bit more elastic, so it stretches more, and allows the anvil to come to rest at a marginally lower position above your head. But only marginally.

In other words, it'd probably a terrible tradeoff to reduce the impact of some disaster by 0.0001% at the expense of making it 0.1% more likely/frequent to occur.

If you have an ~~anvil hanging over your head~~ ton of compressed rock under you, the potential energy that would kill you already exists. Slowly lowering the ~~anvil~~ potential energy of the rock makes sense. Damaging the ~~rope holding the anvil~~ rock containing the energy doesn't.