Compared to the abundance of powers, "Preaching and Solving Doubts" seemed rather standard by the rules of the current world, akin to "Libra-Swearer's" Inheritance, and "Everyone in Yan Country Knows Martial Arts-Source" of the Kung Fu Dream. It could descend upon those who wished for guidance from the Mystical Lord, at most maintaining a sense of presence.
If one had to say it was indispensable, it was that it allowed Feng Xue to descend into this world without needing a doorway, after all, a six-layer villa could only maintain the opening of a single door. Since this world had already been swept by a Kaidan that could envelop the world, it was pointless to continue operating it; better to switch to a fresh Kaidan in another world.
As for Old Li...
As long as Old Li was right in the head, he would stay in this world until he had brushed up on the terms, not to mention the contract between the two was just for a year. Once the year was over, sweeping him out would pose no issue.
