They had the database from the USS Defiant from "The Tholian Web"/"In a Mirror, Darkly".
...which Mirror-Archer said he was gonna delete in the latter episode
So you can do new things with old characters, which could never be done while adhering to the classic continuity. Batshit crazy scenarios where an evil admiral recruits Khan to design superships and weapons to fight a war with the Klingons, or adventures where the Enterprise is attacked and crashes on an alien planet and the crew have to find a way back to a nearby Starbase before it's attacked too.