You know I love to drag Kripke as much as the next person, but one thing his era did very well was consistently characterizing John Winchester as a terrible father and Sam and Dean’s upbringing as abuse.
Seasons 1-5 were not wishy-washy about what kind of father John was. He left his kids alone all the time. He put the care of Sam on Dean’s shoulders almost immediately. He used Sam as bait for a Shtriga and let Dean carry the guilt of it for nearly 20 years. He spent his sons’ college fund on ammo.
He disowned Sam for wanting to go to college. He drank a lot and disappeared for days at a time. He withheld affection from Dean to the point Dean found his father expressing pride in him anomalous enough to pull a gun on him. He considered his revenge more important than his children’s lives or well-being.
He had strained relationships with nearly everyone he knew. He snuck off to take his secret third son to baseball games, leaving his other two sons alone or maybe with a friend. He normalized violence for his sons completely. He is heavily implied to have beaten Dean, who shielded Sam from the same treatment.
He failed to show up when Dean called him, crying and afraid. He failed to show up when Sam called him to say Dean was dying. He ordered Sam and Dean around like soldiers, and Dean visibly shut down around him. He broke promises to his sons. He left them alone with loaded weapons.
All of that and more is established and reiterated throughout Kripke’s era. Dean basically calls him a deadbeat dad at one point. Bobby calls him a coward in season 4. Dean calls him an obsessed bastard in season 3. His absence in season 1 (and for periods throughout Dean’s childhood) is paralleled to Anna’s loss of faith due to God’s absence in season 4 and Castiel’s fruitless search for God in season 5.
Mary is horrified at the way her children were raised. John himself drags Sam and Dean’s upbringing and their father, not realizing he’s talking about his own actions. We even find out eventually that Mary’s death didn’t start the problems, only made them worse. John and Mary were fighting and he left just after Sam was born, leaving Dean trying to comfort his mom at four years old.
He’s written at every turn as a man who abdicated his responsibility as a father and abused and traumatized his sons. And to an astute viewer, Sam and Dean’s complex feelings about their father, their attempts to justify their upbringing, never read as a refutation of that characterization. If anything, they serve to reinforce it.
Hell, their changing perceptions of that upbringing even mirror their character arcs somewhat: as Dean grows more and more tired and disillusioned with hunting, he grows less willing to justify John’s behavior. Whereas Sam, as he grows more enmeshed in hunting and the supernatural, becomes more and more willing to minimize John’s abuse and sympathize with him.
It’s horrible and sad and beautifully done, like the people writing it really fucking understood how abuse affects people and how Sam and Dean’s violent lives and relationships to masculinity are related to the way they grew up and the lessons they learned from their father.
Like we’re not supposed to valorize John or romanticize him or believe he did his best; we’re literally watching the wreckage he left in his wake unfold tragically in his sons’ lives.
And the show keeps that energy through Gamble’s era too. It’s not until Carver and Dabb’s eras that there’s this weird back-and-forth retconning of John’s character, like they wanted to write Sam and Dean moving past their trauma but this time, the writers didn’t understand the material they were working with. Like they didn’t know how to let Sam and Dean heal without handwaving the trauma itself.