Comment by treyd

You're mixing up two issues. The need for oracles is a "hard problem" but it's not the problem in this case.

USDC has a central issuer that can freeze funds because that's the only way you can currently have an asset that "looks like" dollars on a crypto ledger. Someone gets a dollar, mints a unit of the bearer token, and pinky swears they'll redeem it. It's a systemic concern that calls into question the legitimacy of the system, but that's not an oracle.