Bittrex is sort of having the same issues as poloniex.

They used to be two of the biggest exchanges in terms of volume, but now they are overall just mediocre. I think the primary reason is that Bittrex got rid of the legacy account and forced people to verify, which meant that small time traders who previously was able to trade anonymously without any sort of limitations most likely abandoned the platform altogether, since it's not convenient anymore.

Secondly, their support was really bad at one stage and a lot of people weren't able to get their tickets resolved in a satisfactory amount of time, which led to their reputation slip. Bittrex's presence in social media has also just not been there compared to newer exchanges like Binance. They also don't have newer coins listed on their exchange.

It's not necessarily anything bad, since they're still a regulated exchange. It's just that they are not as popular anymore.