51 wins two seasons after 23 wins? He never got a chance. You don't fire 51 wins. If that were the standard everyone lived to, 99% of us would be fired.
It's not unheard of for a good coach of a good team to be fired, if management does not think that the coach is a championship-caliber coach. One example sticks out in my head: In March 2000, the New Jersey Devils, who were then in first place in the Eastern Conference, fired Robbie Ftorek and hired Larry Robinson as their head coach. The result? Three months later, the Devils won the Stanley Cup.
Your argument would make perfect sense, if Kerr didn’t get the Warriors to the finals. But, since Kerr got them to the finals it can be argued successfully that you are wrong and that it was right to let Jackson go. Nothing does more damage to the poor folks in this country than liberal social policies, but try to stop the ‘spending and giveaways’ and it’s argued successfully that you are ‘mean’ and like poor people. Life sucks sometimes, my friend. Heck, as long as were on the topic, I would have never got rid of Hue Jackson.