Will make a very simple, even childish example, why I wouldn't implement an exchanger if I would be a casino owner
Two players came. Player A made a deposit of 0.01 btc, player B made a deposit of 0.01 btc, and both decided to exchange it to xrp for playing. At that time price I (casino) credited to their balances, let's say, 500 xrp each.
Player A had a nice run, made his balance to 3000 xrp and now wants to withdraw it. Where the heck I should get these from, if there weren't any xrp deposited? How much of each coin should I hold "just in case"?
While player B didn't win or lose much, and now wants to exchange his same 500 xrp back to btc and withdraw it. Problem is - prices changed, and now it's worth not 0.01 btc, but 0.012 btc. So I didn't earn from him any, but still need to pay extra from my own pocket?
Ofc sometimes it works in otherwise direction, but still - risk is too big.
They just have to connect their customers with an exchanger which is the 3rd party and it will do the job for those customers that want to exchange their deposits.
It's exactly what I was trying to say