A crypto backed 1:1 by USD is a great idea, the trick is finding a way to actually guarantee the backing currency & exchange rate.
It's actually pretty lousy idea, because in practice it's exactly what we already have in normal banking system, where the "bank-USD crypto", that is, the numbers in your bank accounts, are already backed 1:1 by actual government USD, with government regulations backing the companies and the exchange rate.
If you can freely exchange cryptocoins to USD, there's absolutely no reason to ever consider a stablecoin, unless your goal is to evade money laundering, KYC, etc regulations, hence Tether.
It's actually pretty lousy idea, because in practice it's exactly what we already have in normal banking system, where the "bank-USD crypto", that is, the numbers in your bank accounts, are already backed 1:1 by actual government USD, with government regulations backing the companies and the exchange rate.
If you can freely exchange cryptocoins to USD, there's absolutely no reason to ever consider a stablecoin, unless your goal is to evade money laundering, KYC, etc regulations, hence Tether.