I doubt that is still a problem but I think even if they do something like that, it wouldn't really change much nowadays because they get caught and they simply block the account and the amount of money they earn without paying them. So, it looks like they won on paper but they can't withdraw at all. The only downside here is that someone else would have won, but instead they won and that means the abusers stole someone elses place (in stuff like lottery and so forth).
Of course there could be some people who have won and withdrew as well while tricking the website as well, I don't know how many but there could be some, those are the ones that is danger to the website but I feel like it is not all of them that gets away with it, most of them must have been caught and accordingly punished.
What's the problem?
Limit the faucet the balance needs to be 0 before can use the next faucet, and most of the faucet casino using this method only gives 100-500 satoshi. Did he can withdrawl that's faucet by doing gambling, you need more "LUCK" can be reached a minimum withdrawl by only 100-500 satoshi. Most of the casino minimum withdrawl 50K-100K sat, and the lowest 10K sat.
I believe, if they keep using faucet balance to playing the casino they even cannot reach the min withdrawl without using their own money. They just wasting the time, banned it's not an option everyone freely can create a hundred account if they want. The faster way they can use to got free money, they need gambling using "ALL IN" mode with 4-6x wins in a row using a 2x multiplier.
The calculation ALL-IN should be like this:
Start from 100-500
1x: 200-1000 sat
2x: 400-2000 sat
3x: 800-4000 sat
4x: 1600-8000 sat
5x: 32000-16000 sat
As you can see, if they really lucky and want the faster way they need is to do this method if the faucet gives them 500 sat only need 5x times all in less than that they need more all-in attempt. Cause using an auto betting with only 100-500 sat will not gonna work, sometime me using this method only for fun purpose and cannot past the 3/4x times attempt all-in.