Hahn already replied to you with the two first issues:
- Without regulation you are just trusting some entity to keep the dollars / liquidity
- With regulation, the stablecoin requires a bunch of features:
– Global Freezing Capabilites
– Global Viewing Capabilities etc.
And even if we just ended up in an early 2018 Tether-style situation, even then it would be scary setup: If issuance of ZSAs is private, we will never know how much of ZECTether is minted.
You can also read the discussion here, most of the topic has already been discussed: RFC - Exploring Centralised Stablecoins w/ ZSAs - #6 by JoakimEQ