I’d like to point to the recently implemented features of well-known community tools like Freefoodparty and AOE3Explorer—both of which now have community-flagged cheater lists.
While DLC can revive a game, only a healthy community and solid gameplay can sustain it in the long run.
Anti-cheat is notoriously difficult and expensive for developers to manage, so the most cost-effective solution is to leverage a helpful community group to vet offenders. This costs nothing, and only requires regular communication between the management team and a dedicated group of community members.