Presumably management can (and should) drill down. I suppose it stops middle managers from covering their asses with excuses like "Yeah, I said there was a risk

Presumably management can (and should) drill down. I suppose it stops middle managers from covering their asses with excuses like "Yeah, I said there was a risk of it all exploding, in paragraph 3 of Appendix II". If they find out something important was left out, they know there was an attempt to hide it.