I'm not too involved with the crypto space, but why have a centralized exchange at all? Like why can't the exchange setup a transaction directly between me and the counterparty that we both sign?
I guess that makes sense given that the CEX can simply update values in their own (non-blockchain) database. This highlights that blockchain tech isn't really ready for prime-time use, yet. If the cost / tx could be brought down significantly, then there would be no need for a CEX.