First it is Payton, not Peyton. Second as I have said many times before... McDermott has never lost in the playoffs to a team his Bills were clearly better than. Quarterback wise with a not quite elite Allen he lost to a pre legal issues DeShaun Watson and then since Josh reached elite status he has lost twice to Mahomes and once to Burrow.
Sean Payton with Drew Brees (a first ballot HoFer) lost to Rex Grossman, Matt Hasselbeck, Case Keenum, Kirk Cousins and Jared Goff.
If McDermott was losing in the post season to teams QB'd by those sorts of guys I can only imagine the reaction.