Anakin / Darth Vader is purposefully re-contextualized as a kid, and I think there is some value in foregoing the fabled ‘Jedi Hunts’ (that were sure to have happened between canonical III and IV anyway) to examine what made the monster at earlier psychological and political points. He’s a failure of institution, radicalized by war, exploited by an abuser, abandoned by pedagogy. It’s a different flavor of tragedy than personal failure.
Anakin’s downfall should probably contain elements of both systemic failure and personal failure. But I think it should be more heavily weighted towards personal failure. Perhaps something like 40% systemic failure (failures of the Jedi as an institution, experiencing the horrors and injustices of war, etc.), and 60% personal failure (Anakin just being turned on by the allure of power, and his need for control in a chaotic Universe). The greater emphasis on personal failure is really required for Vader’s redemption in ROTJ to have real dramatic weight. It really needs to be Vader’s choice to embrace the Dark Side, and also his choice to save his son in ROTJ.