I'm just curious, why do exchange always attempt to create new kind of cryptocurrency that can replace USD?
In my opinion, It's much better if you can just convert it directly to USD, so trader may assure that their money in the trading site is really equal to 1usd.
What is your option on this matter?
The answer is blockchain. USD is a fiat currency which doesn't have seamless integration with the crypto exchanges. Stable coins backed by USD moves within the blockchain to provide necessary liquidity to the traders and to allow them hedging against the volatility.
Also there are many legal constraints to convert the cryptos into USD and transfer it in to a bank account located in US. Not every exchange is authorized to do that! Nowadays I have seen few exchanges are trying to build similar stable coins and I have seen two ICO with the similar plans. But I really believe that the presence of more than one stable coin will not do any good to the market unless they are able to provide liquidity to the traders. Those will just be another coin among the lot and nothing else!