That is simply a function of more O coaches being hired as HCs over that time. Lynn, Marrone, O'Brien, Gase, Pederson, Kitchens, Garrett, Shurmur, and Jay Gruden are coaches fired the past 2 years with Jon Gruden joining them this year.
And of course it is relevant. The goal is sustained success. Those Non-O coaches have super bowls. The guys you referenced do not.
All you are doing is cherry picking examples that fit your narrative. Plenty of Omcpaches fail. Some succeed. There is no real evidence that going with an O coach is an advantage. It is just your preference.