In my opinion, there is a difference between receiving a payment directly from a casino's address or receiving a coin that in the past has been withdrawn from a casino.
The former is normal business procedure: some businesses are simply not allowed to receive a payment from a casino, be it in crypto or fiat. That's nothing new.
Bitcoin is supposed to be electronic cash. If I get cash from a casino, there's no way anyone can know, and nobody is going to refuse my cash for that reason. Ideally, Bitcoin should be treated the same.
Yes, cash is my benchmark as well. Hence I'd like coins that have been withdrawn from a casino into a personal wallet, to be accepted anywhere.
It's just that if you 'withdraw' from the casino directly into an exchange's 'deposit' address, you never 'had the cash in your hands', and it's basically a direct money transfer (think: bank transfer) from a casino to an exchange. Since most businesses wouldn't accept bank transfers from casino bank accounts, I can see how they don't want the same through Bitcoin.