Qingshan Village was his home, where everyone knew each other's origins, and they all placed their trust in Wang Sheng. Therefore, Wang Sheng was able to directly open up his Spirit World and even directly pull people into it.
But for outsiders, the situation wouldn't necessarily be the same.
The issue wasn't that Wang Sheng feared not being able to cover the bases, but rather that outsiders might not trust the existence of the Spirit World.
Intelligent beings are prone to overthink; if it is a process they can initiate on their own, at least they feel it is within their control.
But if someone were to guide them in, they might suspect a plot or even feel that their Cultivation might benefit someone else.
Although as long as the effects were positive and significantly helped cultivators, the impact wasn't especially big, it was naturally better if such concerns could be avoided.