Indeed. But you must, at some point, withdraw both currencies from an exchange in order to balance your overall inventories... So if you can never withdraw one side, I fail to see how you can arbitrage?
You must withdraw them at some point, or transfer them to another exchange or in some tangible way retrieve your earnings. This does not mean that you must acquire them in USDT or whatever else though, you can take it as it comes; Make it work with the rules and regulations that are present on both exchanges.
Arbitrage is much harder if you simply go about it straightforward and head-on. This is what everyone else is doing; if you can find a way to make use of two different currencies, rather than try to consolidate them and eat more fees, you might just have a better chance. You have to think outside the box. You may not be able to withdraw the one side as you'd like, but does it offer another option to retrieve your funds, and if not then why are you there in the first place?
