The buck stops here is how I see it.
If you bought a house "as is" and you knew the roof needed repairs, but you neglected it for years until it finally leaked during a strong storm, the previous owner has no blame in this. Its on the current owner.
It's more like you own a house with a tree out front. You have a yard guy that you pay to take care of your yard.
One your neighbor drops by and says that your tree's getting too call and needs to be cut back. You ask your regular yard guy and he says that no, those trees have deep root systems and it'll be fine. Your neighbor suggests you bring an arborist in to check, and the arborist also says that your tree is fine.
Then there's a big storm one day, and the tree gets knocked into your house.
Now you're blaming the homeowner, even though multiple experts all said the tree was fine w/o cutting it back.
Again, you just seem eager to assign blame when there's not really evidence that warrants it. Hindsight is 20/20, but the experts involved at the state and federal government level did not deem that any such work on the dam was warranted.