As far as I know online casinos, if you withdraw funds in the form, network.
BTC  - Bitcoin
ETH  - Ethereum (ERC20)
BSC  - BNB Smart Chain (BEP20)
POL  - Polygon
SOL  - Solana

It seems that everything is clear and I think the crypto casino does not want to bear the costs charged by the network I mentioned above.

Although the cost is fairly low such as a sole or BTC network, only 0.5 sole and 0.00001571 BTC, but if it multiply 1000 users make withdrawals every day, I think the casino does not want to be responsible for it.

But one side, yes, if the casino wants to bear the burden of the cost, maybe some gamblers are happy, but the casino does not think of just one person, thousands are not good ideas for casinos, for us yes.