But then you are no longer decentralized, since there is a third party (the escrow) who has complete control over your coins. The advantage of a platform such as Bisq or LocalCryptos is their non custodial escrow set ups: 2-of-2 multisig between buyer and seller in the case of Bisq, and a locking script requiring codes from both buyer and seller in the case of LocalCryptos. The only way to cut this out altogether is to trade directly with another person, which is fine if you know and trust them, but often that isn't the case. I don't see how a fiat supporting DEX wouldn't become a haven for scammers if it had no escrow.