Do you want to withdraw with profit or without? If I may ask.

Maybe there is no liquidity? Just guessing.

Definitely typical if the wallet user is not owning his private key. Not good. Third party. Trust is not so easy. See WireCard.

Somehow I feel like exchanges have a lot of work to do. Or atomic swaps on the blockchain via lightning come first. This would have implications for exchanges for sure as then the blockchain itself or off chain smart contracts would be the exchange. No third party exchange needed.

I am just speculating of course. Who knows future?