Doing KYC and not doing have advantage and disadvantage, the advantage is for the exchange to weed out bad people, knows who they are dealing with and help to fish out users from countries that have been sanction, that is the benefits of doing KYC to any exchange. The disadvantage here is that exchanges are known for non-transparency, they can do whatever please them with people information. I have read where Binance leaked users KYC on the internet that was trending for weeks, such things are the thing we fear of not repeating by other exchanges.