Not introduced by ethereum, it's just done on top of it. There were several dapps trying to make their own pegged currencies on ethereum, but I wanted to unify it with the right formula to create a token to use on ethereum dapps (since the market pegged design is the superior way to do it). It will also partially be leveraging the stability of bitUSD to reduce risk (assuming it becomes possible for the contract to hold it with a two way peg).