Cryptocurrencies have an advantage over electronic U.S. dollars in decentralized electronic transmission. I don't think that's a big deal, but the advantage exists.
Stablecoins, on the other hand, have zero advantages over U.S. dollars. Backer goes bust, someone steals the dollars, someone freezes their accounts, et cetera and your currency is worthless. A trusted third party rests at the centre who is less regulated and guaranteed than a bank.
(I'm sceptical that these schemes will pass AML muster. Using a stablecoin over U.S. dollars makes sense if you're (a) incompetent or (b) laundering money.)
With access to an oracle for the USD value, you could make a pretty decent stable coin in Ethereum. You could also create options that trigger on USD-ETH values. This would allow for some hedging against price-moves of ETH without being full-on pegged to the dollar.
Stablecoins, on the other hand, have zero advantages over U.S. dollars. Backer goes bust, someone steals the dollars, someone freezes their accounts, et cetera and your currency is worthless. A trusted third party rests at the centre who is less regulated and guaranteed than a bank.
(I'm sceptical that these schemes will pass AML muster. Using a stablecoin over U.S. dollars makes sense if you're (a) incompetent or (b) laundering money.)