I think one of the reasons why they prefer not to is such game guard tools usually get detected as malicious programs by antivirus. So they need to provide additional supports on how to whitelist xiv in antiviruses for the customers ON TOP of having to spend development resources in building and maintaining such a tool.

Considering how most players in this game dont do high end contents and theres no esports for it, the cost of adding it outweighs the benefits of catching several baddies who would get banned if they participate in World First clears anyway since it is often recorded as a proof.