Someone cannot not say to them "let me understand, you are claiming that it's not Brexit that failed, but that you are incompetent?" because these people were not in a position of power to do anything differently. The mismanagement of Brexit is down to Theresa (Lino) May and her beloved Ollie Robbins KCMG CB. The negotiations were weak to start with and then went south from there. Even Johnson knew that to "get Brexit done" there could be few deviations made from the useless so-called Chequers Agreement, else there would be another 5 more years of pissing about.