The reason for adding Faucet to online casinos was not like that. Faucet was invented for the purpose of allowing users to check out games without a deposit.
There are several sites I have visited that allow withdrawals from Faucet. But on the other hand, there are many sites that allow, but according to their rules.
E.g., DuckDice. They allow users to withdraw from Faucet, and sometimes deny it. Users who make regular deposits, high rank level, they allow them to withdraw up to 5 bitcoins. On the other hand, those are new to the site. Just playing with Faucet, their withdrawal denies. Casino Royal Also has same system. Imagine for a second, you were added Faucet so that customers could test your site, but they withdrew a huge amount. What will you do then?
I have seen many sites like this, who initially came up with the site with Faucet, but later they were forced to shut down Faucet. Such as Bitsler, Jacksclub,