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.
Yeah, you do not need an oracle for USDC.
But I don't see USDC being mentioned in my reply or the comment I replied to.
And calling the need for oracles a "hard problem" is a neat euphemism the point of which escapes me. It's not solveable.
As someone else wrote: when something goes sideways with their assets the crypto posse call for law enforcement. Or they bent their own rules (DAO/ETH hard fork, 2016 e.g.).