Are you sure about that? DEX created to have a full decentralized approach but it is not yet vulnerable to scams what do yo think happened last time on etherdelta which was compromised during the time many got stolen by phishing then the management was clearly destroyed due to its big event that time? I think dex is nice system but of course the process isnt perfect yet as we all know it.
But all can still be anticipated, even though their user confidence declined very much. the problem was based on phishing / dns that were hijacked, and now all can be anticipated by using ledgers or metamask. Their management does play a very important role but dex security is still better when compared to cex.