Auditing the supply would mean transaction amounts were public. That kills privacy. Theres a reason exactly none of the privacy coins, including Zcash, Grin, Beam, Monero and Mobilecoin do it. Hiding transaction values is table stakes for getting privacy right. (but not nearly enough. see https://slideslive.com/38911785/satoshi-has-no-clothes-failu... and https://www.monerooutreach.org/breaking-monero/poisoned-outp...)