Nobody is saying you shouldn't have a good understanding of the bridge that was built.

The argument is that you need to understand why it failed, in the lifecycle between what we intended to build vs. what we built.

There's a massive difference between a bad design and bad materials, both of which could have caused it to fall.

You can get a bad design idea from the code/bridge as well, but it's pretty glaring when the intent said, "we believe balsa wood is the best bridge material", or "we decided to save 49% of our costs by getting our nuts and bolts from the Lego shop."