It's not like there's just some "go_slow=true" constant that just needs changing.
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.
There are tools for creating automatic LODs that come with their own pro's and con's. A bad LOD chain can express itself as really obvious pop-in while you're playing the game. There's also these things called imposters that are basically flipbook images of an object from multiple angles that can be used in place of the true 3d geometry at a distance. Those are created automatically. They tend to be like 4 triangles but can eat more vram because of the flipbook sizes.
Unreal engine has nanite, which is a really fancy way to side step needing LOD chains with something akin to tessellation, as I understand it. Tech like that is likely the future, but it is not accurate to describe it as the "way most games are made today"
However, I also find the suggestion that because there are other high profile examples of unity projects with performance issues, it must be a problem with unity.
You don’t hear that about Unreal Engine, despite the fact that there are poorly optimized UE games.
Such a bizarre set of assumptions.
It definiitely has much to do with how UE's PR constantly shows off and ships new and exciting features that blend in the engine. Meanwhile, Unity has been criticized for some 6+ years minimum for its package management and lack of cohesion.
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.