These two types of life destinies are suitable for cultivation because—
The former has an extremely tough fate, with exceedingly strong yang energy; general fierce ghosts don't dare provoke him. In fact, when they encounter him, they might end up losing their lives. Therefore, he is naturally fit to catch ghosts and subdue demons.
The latter's fate is too yin, innate ability to communicate with the Netherworld, and life destiny is between yin and yang, making them naturally suitable for traversing the underworld.
Moreover, due to their yin-heavy life destiny, they are prone to being targeted by malevolent entities. If they don't cultivate and simply live as an ordinary person, they become a natural vessel for evil spirits, likely to experience events such as soul loss or ghost possession.
Thus, only through cultivation can one ensure their survival.
In summary, these two types of destinies are indeed very suitable for cultivation.
However, such destinies are not commonly seen.
