agree with the above post. I think what the Author is trying to say is that people will do horrible things if
it is seen as acceptable or the norm by society's standards. The story is meant to comment on how easily people willing go along with the crowd and do things that can't possibly be right or good because everyone else thinks it's ok. Just look at how quickly people are willing to abandon their own morale compasses and murder another person, knowing it to be cruel because the "group" is doing it. In the story context it's been going on so long it is seen as normal, which further shows you that the longer nobody steps up and makes a change the farther society will decay.