This write-up really points the finger at not solving occlusion culling or having good LOD discipline.

Give a person a dedicated optimization mandate and you can avoid most of this. One of the first things I do when I'm profiling is to sort assets by tris count and scan for excess. I wonder if they had somebody go through and strategically disable shadowcasting on things like those teeth? I am guessing that they made optimization "everybody's responsibility" but nobody had it as their only responsibility.

The fuck up here is whoever was handling the art assets. You simply do not ship a game with such detailed graphics and no LODs. They must've simply been downloading things off the asset store and throwing them in without any regard for performance.