A Supreme Grade Innate Spiritual Root from a Great Thousand World contained the Origin of the Great Dao, equivalent to carrying original shares. Therefore, Supreme Grade Innate Spiritual Roots were not permitted to leave that Great Thousand World.
Otherwise, it would amount to permanently losing that portion of the Origin of the Great Dao!
How important was the Origin of the Great Dao to a Great Thousand World?
Therefore, if one used a Supreme Grade Innate Spiritual Root from a Great Thousand World as the Root of Five Qi for a Golden Immortal foundation, then unless one could defeat the Heavenly Dao, one would never be able to leave that Great Thousand World!
Unless one destroyed one's own foundation and returned the portion of the Origin of the Great Dao integrated into the physical foundation!
However, so long as one had yet to comprehend and bear an Origin Great Dao, whether it was the physical foundation or the primordial spirit foundation, it was still easy to reconstruct. There was a cost, but it was not too great.
But once one broke through to the Grand Unity Golden Immortal realm, the physical foundation had already transformed into the Flower of Essence, while the primordial spirit foundation had transformed into the Flower of Spirit. Essence, Qi, and Spirit gathered as Three Flowers at the Crown, and the True Spirit returned to unity.
At that point, it was still possible to reconstruct one's foundation, but the price would be immense!
With even the slightest carelessness, the Three Flowers of Essence, Qi, and Spirit could all be damaged, weakening one's foundation and leaving one's Grand Unity Dao Fruit on the verge of collapse. One might even directly fall in cultivation, dropping from the Grand Unity Golden Immortal realm to the Grand Unity Golden Immortal