Value will be created with the deposed US-dollar.
If you buy cryptoDOLLAR, it will cost 1 USD and that 1 US-dollar will deposed on safe and never used.
But if cryptomarket crash, or no one don't want to trade cD anymore, you will get that deposed dollar back. I think cryptoDOLLAR realistic value is then 1 usd.
If it's well operated & trusted by people for some time, the value will exceed 1 Dollar, and you don't have enough reserve to keep the price at 1$. What you will do? Fork more so-called cD-2, cD-3?
Attach to the USD is not a good thing. You might forget the famous Liberty Reserve. Or you are a child not knowing it.