Because they don’t care about performances. They just want you to not pirate the game for the first couple weeks after release so they can make the most sales money, then once the crack is out, they remove Denuvo…or not.
The security is for their benefit not yours, so they don’t have a reason to trust your hardware over proprietary software they control.
But maybe I’m wrong, I’m just assuming. I’m not a dickhead using Denuvo.