They already had their version, it was called the Relic Reborn quests The Chimera and The Hydra in addition to coffer hunting. The entire world was your carnivale.

Carnivale is not for a weapon, the majority of their toolkit will be acquired there. One job getting a big unique content like this is intensive. If you go back and do that for every job the workload increases.

Do you want to start questing all your skills with RNG acquisition for Monk or Scholar?