He wanted to "preserve the culture". The culture is meaningless without Payton and he can't accept that. Hell, the "culture" was really meaningless without Brees, tbh. We should have had the stones to roll the dice on a new regime once SP left.
But now we're here with DA and Loomis seems pretty resistant to change even with all the evidence that it's not going to work.
Loomis won with one specific coach and QB combo. He just got lucky that they stayed here as long as they did. His record outside of that isn't stellar.