Tether and other pose a critical systemic risk to all cryptocurrency. Anything to increase trust/transparency with stablecoins is a big with for crypto.
Tether could end all of their "FUD" if they ever published such a report.
Circle's reporting: https://www.circle.com/en/usdc#transparency (edited to change audits --> attestations)
I see Tether heading towards collapse, not legitimacy, and any actual increase in transparency would just hasten the collapse.
I still think a third-party attestation provides a lot more trust than the shady-stuff going on with Tether.
You want an audit. I have been there, seen the procedures, run the numbers, and independently verified that when followed yield the same result as reported.
It's the difference between "Seem's legit" and "The numbers check out".