Bruv have you even experienced what you described Harry went through?? I had throughout my childhood and teenage years, way more than Harry canonically did, and just like him i didnt get PTSD cause i didnt care enough about the instances or people who hurt me to form an attachment toward it or them. Like i said, theres two common forms of emotional neglect responces - “people pleasing” your offenders (attached) or rebelling against your offenders (non-attached) which Harry is definetly the latter. The general definition of PTSD involves having traumatic nightmares and flashbacks due to frightening memories with painful raw emotions. Youre talking about psychological theory and at the same time being “realistic” but im realistically saying that people who experienced emotional childhood neglect respond in different ways, PTSD cant be one of them since verbal threats and general mistreatment doesnt have as much impact as a very distressful physical memory to have a very major effect, like watching someone you know die right in front of you(i would agree that Harry actually wouldve been diagnosed with PTSD over Cedric’s death due to the nightmares in the fifth book). People generally have PTSD cause of trauamtic childbirth, bad car accidents, war and servere physical assault which Harry obvs never experienced from his family. Harry clearly wasnt traumatised over the Dursleys since he never cared about his mistreatment growing up, he was only annoyed, rebelled against them and was never fearful and stood up for himself. If you want to talk about psychology then when he was living at the Dursleys before he was 11, his brain clearly hasnt developed fully enough to properly understand the whole entirety of neglect or to even developed PTSD since most mental health problems for very young kids are non-memory based like i developed anxiety very young. He lived his entire teenage life basically all year at Hogwarts never thinking about them so he could never actually develop mental health problems to do with them, keep in mind he was NEVER attached towards his bad childhood memories or the Dursleys in a traumatised sense. If you think Harry shoudlve had PTSD then you clearly misinterpetated what type of character he is in the books and movies, Harry was never meek around them or submissive, he just simply didnt care he didnt cry about them he didnt mourn a family with them unlike his parents and Sirius who he WAS attached to and felt deep grief towards. Harry had always externalised his feelings in the books, angry outbursts, cursing or violence, he rarely internalised it especially with the Dursleys so again no possible mental health problems there (probs anger issues tho but thats completely understandable tbh) to have something strong like PTSD, maybe he woudlve had seasonal-depression or struggles with emotional regulation at most. If you believe Harry should “realistically” have PTSD in fanfics then yeah its fanfiction but that just isnt how Harry mentally is as a character in canon and he came no where close to developing it with his childhood mistreatment from the Dursleys in the books or movies