The position of the master of the Seven Treasures Mysterious Garden concerns news about the Great Bright Hall, and the secrets hidden within the hall that enable ascension to the Immortal Realm—a matter that is no secret within the cultivation world.
For the Three Pure Orthodox Sect and the Six Path Demon Cult, as long as someone from their sect ascends to the position, they can ensure access to firsthand information.
However, for other third-party sects, it's obvious that the Three Pure and Six Path factions would never share the information with them. After all, even after gaining access to the Great Bright Hall, there would still be fierce competition. Fewer rivals would naturally be better.
Thus, whether entrusted by Scattered Immortal elders or driven by their own nearing perfection in the Nascent Soul Realm, nearly half of the cultivation world's Nascent Soul cultivators have gathered in the secret realm to vie for those scant twelve slots.