Here in our country, the most popular local crypto-exchange here requests for those queries as part of the mandate by our country's Central Bank. In the past, it can only be triggered if someone hit the "alarm" but today, I think the majority of their users now required to submit such queries. I comply with that as I regularly used that exchange, not just for crypto but for other services as well, and no-hassle or worries hitting the alarm unlike before that for just around $1,000 or $2,000 withdrawal in a single transaction, there is likely you will be asked for an interview right away lol.

Going back to Bittrex, it's up to you to decide, do you use them regularly? Do you currently have active funds there? If NO, then simply don't comply and stay away from that exchange aside from the fact that other users here don't have a good experience using that exchange.