Why do you have to zero out balance to withdraw a certain way

I have only seen this at one place I play.  I am wondering how many places actually have this policy in place for their withdrawals.  At this casino if you deposit with a card you must withdraw your earnings to your bank account. On the contrary if you deposit to your account with crypto you must withdraw with crypto.  If you don't withdraw and wish to change your withdrawal method your balance must be played down to zero before you can deposit/withdraw with a different method. This is at Stake.US btw.   I am just wondering what purpose this actually serves and if its based in any sort of legality or if it is only one of Stake's rules?

The policy you are experiencing is called a "Closed-Loop Withdrawal Policy", and seems to be the standard. I think it has something to do with money laundering ( dont aask me how ).

That makes sense. From what I've read, closed-loop policies are often tied to anti-money laundering (AML) and fraud prevention requirements. If casinos allowed someone to deposit with one method and withdraw through another, it could potentially be used to move money between financial systems without much actual gambling taking place.

What I'm curious about is whether this is an industry-wide requirement or just how certain operators choose to comply with regulations. For example, many casinos require withdrawals to go back to the original payment method when possible, but Stake's rule about having to play your balance down to zero before switching methods seems unusually strict.

Has anyone seen the exact same policy at other online casinos, especially crypto-friendly ones? I'd be interested to know whether this comes from regulators, payment processors, or simply the casino's own risk-management policies.