I think you missed the “despite all his efforts” - I’m trying to make a backhanded defense, along the lines of “You were a shit parent, but hey, your kid was alright, so I guess you failed”, but I phrased it awkwardly.

I very much know your position though. Someone close to me had a similar issue with their parent, who forced them to become self-reliant since the parent in question was neglectful at best.