Currently some top exchanges have decided to launch their Stable coins instead of using the Tether. Huobi has launched HUSD. Binance Launched a stable coin but choose to call it a new stablecoin market USDⓈ. they are yet to list the market pairs.
What is the reason behind this latest?
It's all about business, pairing in BTC or ETH is goo but with an addition of Fiat pairs it would make the trade more accurate. Though some would prefer a pairing in crypto to crypto but we should adopt in current market where in paring with BTC would spend them lots of it and cannot gain profit if bullrun start.