Emm, that doesn't make any sence. What's the difference between paying the fee in base currency and paying it in some other currency? If you sell 100 USD for BTC with 1% trading fee so if you sell 100$ worth of BTC you will still loose this 1$ worth of BTC. It btcome even more complicated when it comes about altcoins where the exchange will have to exchange this fee to the mystical "fee currency".
P.S. As i remember Kucoin also have the same feature that was described by lite.