The point would be to provide a more legitimate USD stablecoin in a space that seems to be attracting a growing user base (blockchains). I imagine a significant share of the market would choose the Fed-provided stablecoin over any of the non-Fed competitors. If you're using US Dollars in the first place you're already inherently trusting the Fed, so it shouldn't be a much bigger leap to also use their blockchain-based version. This would reduce the degree to which Tether and others are "a challenge to financial stability" because it puts mint/burn powers of the dominant USD stablecoin squarely back in the control of the Fed.