It is common for the Immortal Village to have defensive arrays; after all, they are like rats scurrying across the street. Once discovered, without any defensive measures, they would easily be wiped out in one fell swoop, with nowhere left to run.
Arrays are not absolute necessities, but one simply cannot survive without them, especially for a group like the Immortal Village.
One must remember that Elder Xiao has held a grudge against the Immortal Village for many years. A trait shared by the Xiao Family is their tendency to be fiercely protective of their own.
Chapter 480