Arguably, the point that the author is trying to convey in their work of literature is more effective when it is implied and not stated. Clearly, when we read this story carefully, we see that the thesis of Jackson is definitely not overt or stated. We have to re-read this shocking story to piece together some of the clues she gives about what she is actually trying to communicate. The horrendous act that culminates in the ritual sacrifice of Tessie Hutchinson is shown to be the result of unthinking and uncritical obedience to the dictates of tradition that overwhelms any moral conscience or sense that the villagers might have. This strict adherence to tradition causes even Mrs. Delacroix, Tessie's friend, to pick up a stone to crush her friend's head with that is so big that "she had to pick it up with both hands." Everyone is involved, even little Davy Hutchinson.
Arguably, this story is more powerful precisely because the thesis is implied, not overt, and because we need to piece it together, looking again at what tantalising clues Jackson gives. This causes us as readers to engage with the story in a way that we wouldn't have to if we were given a stated message without having to work to understand it.