To be fair, it's hard to know how much the Comey letters and the years long assassination of Hillary Clinton's character had an effect in the election. Not to absolve her or her campaign for some glaring mistakes, she lost by such small margins where it mattered that they could probably still have snatched it if they didn't bought into their own hype, God knows she had the financial means to try to secure more votes in the "blue firewall" states that failed her. Hindsight is 20/20 but it is interesting how Clinton's campaign was so ambitiously offensive on the electoral map (hoping to win one or several of FL, NC, GA, AZ) while being so defensive in the discussion because Trump sucked all the air in the room and was the main attraction.
Republicans have some responsibility in discrediting politics and laying the ground work for Trump.
Also, I said previously that analysing stuff as slogans in light of the defeat is obviously gonna be colored by confirmation bias, but really "I'm with Her" was awful messaging.