I suspect bittrex has been unable to upgrade its systems further, although they have transferred the technology to Bitsdaq as a new trading platform. They do not try to find ways to change their mode of operation. The first is that they do not have a model to enjoy commission of transaction fees from introducing new members. Their transaction fees are higher than other exchanges by 0.25% higher than Houbi, Binance.
Because they registered a company in the US, it was more difficult to allow them to launch Bittrex's own token, with too many rules.