Some casinos use KYC as an excuse to not let you withdraw your winnings. For example, imagine that you made a deposit, won a huge amount of money and want to withdraw, then casinos ask you to submit KYC because they think your funds are suspicious but in reality, they gamble with you with the hope that you'll give up on your winning because of KYC requirement. Sometimes, even when you submit KYC, they still make the withdrawal procedure very hard for you and ask for additional proofs, video calls and etc...
All of these usually get resolved when you open a scam accusation thread on Bitcointalk but in that case, the casino must be active here and should be oriented about their trust here.

FortuneJack is considered to be a trustworthy casino but one user was complaining about not casino not letting him to get verified first before making a deposit.