A Joyce Carol Oates story w a ridiculous conclusion

Joyce carol Oates is one of the most prolific writers in america so of course she has hits and misses so why would the editors pick her 1969 story By the River to represent her work in 100 years of th best american sho stories? The story starts off so well and seems at first to be a fair example of oates's sympathy for struggling working-class people - in particular in the small rural or agrarian towns not often represented in literary fiction: a 22-year-old woman retune to her hometown after the breakup of her marriage and the end of a brief affair w an older man.  She is waiting at the dreary bus station for her father to pick her up and take her back to her childhood home, a poorly constructed farm house set on unproductive land (interesting contrast w Updike and his childhood move to a rural setting). The story is largely her interior monologue and after father picks her up at the station his lament , at first taciturn but building into almost a screed of anger and resentment at his I laws and at all the other farmers whom he considers the "rich," - along w some ominous hints: he hasn't even told his wife that their daughter is coming home. So far so good and the he stops the car and the two of them walk down to the eponymous river - a nasty and mucky choked stream - there is nothing pleasant about the pastoral anywhere in Oates - and (spoiler) he tastes out a knif and stabs his daughter in the heart. Now I know jco is fascinated by violence and that anything can happen in life and in art but seriously stabbing his own daughter? For no reason other than many expected he's ashamed because of the failure of her marriage? W no preparation or even foreshadowing that he is homicidal? Truly a ridiculous end to a character sketch that jco had no idea how to use or develop.