The reality is that we all make mistakes. Even when we have the best intentions, best plans, and best execution, something falls through. You shake your head and say how did it happen, what could have been better, what could I have changed and so on.
By accepting responsibility, we feel less of the weight on our shoulders and less guilty. By denying responsibility, we shift the blame to others, circumstances or something beyond our control. The energy and time taken to prove someone else or some external factor was responsible for the outcome is draining even if that was the case. The better move would be to accept responsibility, work on improving next time, and just move on. When we accept responsibility, we also become self aware, transparent, and relatable .