Fucking scam exchange services and scam casinos. It is a fucking scam if you are not going to require KYC before the initial deposit and then require it when someone tries to withdraw.
Either require KYC from the first signup or don't require it at all.
These fucking selective scammers are pulling this shit for too long. These bullshit "webwallets" and "casinos".
Read their TOS very carefully in the beginning so that we won't go to the hassle of sending your KYC info if you don't link. But I would say that yes, it is a shady practice by some exchanges and casinos in beginning. When you sign up, there are no warnings. And when you try to withdraw specially in a casino wherein you won tons of bitcoin, they will suddenly enforce KYC and will 'delay' your withdrawal. You are lucky enough that you can withdraw, because there could be casinos that are going to suspend your account for no reasons at all.