Crisis can affect the speed of thought.
From the activation of the first Void Portal to the descent of nearly ten million Void Monsters, it took only about fifteen minutes. The time they had to make a decision was less than a minute.
It was only by making the right decision within this minute that the crisis could be averted.
Although there were sporadic comments in the live broadcast pointing out that the crisis could be stopped by surrounding without killing, only a few people mentioned it.
Most people only knew of the horror of the Void Clan but were not aware of the details, and even if they were, they did not think of stopping the continuous replication of the portals in this way.
Moreover, they were watching from the perspective of bystanders.