Most blockchains have a common problem where blocks can be front run as the block producers/validators have full control on the ordering of transactions.
If blocks can be front run, it is unlikely a large DEX (if non AMM - automated market maker), could work as it would be impossible to determine which order came first fairly, to execute trades. Don’t event mention HFT.
Tezos has so much potential as a functional programming based protocol etc with michelson, to take lead in DEFI, but I think this needs to be solved.
Hedera hashgraph does have a cool solution for this as it takes a medium timestamp of all gossip validators. I have not seen a similar solution for eth.