After the complaints of a lot of gamblers years ago. We have seen a lot of crypto casinos that implement the concept of simple KYC when new user register on their platform, but they later request the main KYC when a huge fund or winning is involved to prevent future issues with the authority. This concept was presented to avoid minors using their platform, and to prevent their business from having issues with the law.
It has become a common concept to think that whenever a casino freezes your funds and asks for the KYC, that the casino is tying to rob you, steal your money unfairly. We can see countless scams and accusations related posts in the reputation board. But that is not the case always. Most of the time these disputes are solved and the user gets his funds back. If not then the case didn't had solid/reliable evidence. But at the end of the day, this misconception still remains in everyone's mind that, the casino will rob you by asking for KYC when you win big and try to withdraw it. And if I'm guessing correct, this is why the OP is asking for the KYC to be done before user can play. At least in this way, they won't have the fear of KYC being failed or what they think of.
Oh ok. I guess you're right about what the OP truly means, but the last time I checked, all the reported complaints in the scams and accusations section were always treated fairly, not based on what the accuser said, but the evidence and the casino's clearly stated TOS.
Based on what you said. Business-wise, no casino will ask for full KYC from the new user after creating an account when the user is yet to make a deposit, otherwise they will lose a lot of new users.