Every Titled Truth Wizard was a powerful wizard who had tread a unique path of the Law, comprehended the true essence of the Law, and possessed a vast reserve of knowledge.
Even with the power of the Wizard World, Truth Wizards were not an existence to be taken lightly.
Additionally, each Truth Wizard, at the moment of their ascension to immortality, would connect their own Truth Law with the Heavenly Dao Laws of the Wizard Great World. This allowed them to benefit themselves while also using the many Truth Wizards to improve and even strengthen the Power of Laws within the Wizard World.
This was a mutually beneficial arrangement, and no wizard would forego the immense Wizard World in favor of other, smaller worlds.
After all, the Laws in smaller worlds were relatively flawed and constrained their growth potential.