^^ In a word, "Election 2016" ^^ Occam's Razor: there was not a slew of sophisticated reasons dems lost. The reason was quite simple, given that simple folk gave us the results of 2016..
What dems should do is simply scrape off the LGBT barnacles that lost them this election, & focus their platforms away from a deviant sex cult. Because if they don't, they're going to keep losing as the normalcy is restored to this nation. Essentially, because of what we know the GOP will do with the High Court appointments, they have no choice but to come back to sanity and tell their weird sex-cult friends "get help, boys are not girls, men are not women, two men or two women do not make an adequate mom and dad for kids". Either that or face extinction.Think: Target Boycott & that California voted down gay marriage TWICE, the latest in 2008; which was not that long ago.
And this scrubbing process is going to be interesting to watch because they are in bed so deep with patent insanity that it's going to take some VERY non-PC conversations with their base to clean off their logo..
This is why the dems leaders are in such a state of panic....THEY KNOW EXACTLY WHY THEY LOST, and it means facing that pernicious and insidious tantrum-throwing bloc of their base and telling it like it is. If it were me, I'd form another party called "the new democrats" and tell anyone else to go pound sand. Obviously that old rainbow bloc cannot vote for another Trump in the future; because of what will happen to their pipe dreams if they do. And once they see that A JOHNSON VOTE IS WHAT STOLE THE ELECTION FOR HILLARY IN EACH AND EVERY KEY BATTLEGROUND STATE SHE LOST....maybe just maybe they'll come back around to sanity. But it's going to take a couple of generations to undo the LGBT brainwash to the millennials and others.
If it were me, I'd form the new party name, begin an ad campaign from DNC funds to teach the little voting kiddies what happened in 2016: how their votes cast for Johnson exactly equaled, state by state (it was eerie, google it if you have time) the precise amount of votes that would've won the state for Hillary instead of Trump. Educate them about disloyalty and how it's cutting their own throats. Then wait for them to come back to the fold.
It's a gamble, but since they're going to lose 2018 & 2020 in exactly the same way (no matter how much they skew...or outright lie about... the polls and don't discuss the elephant in the living room), it's worth a shot. Otherwise they will face this hidden majority who eat drink and shit common sense; and 2016 will happen over and over and over and over until they finally face facts and do what they have to do.
It's going to brutal. No doubt about it.