In politics, you don't get points for always being right if the perception is you're wrong. It may be a shitty situation, but that's the way it is. A lot of people, myself included, had issue with some of the rhetoric Bernie's campaign has used to explain away areas of the country in which he didn't do well. If you are claiming you don't do well in "conservative, Southern states" but championing how well you did in Kansas, Utah, Alaska and Nebraska....it's only logical for people to ask what's the difference between these two. And the difference is obvious. Again, though, I don't think Bernie is racist or hostile towards AA, Latino, gay or women who don't support him. I think he's often tone deaf because he gets to hid behind white, male privilege. (Which is why his main issue is income inequality because, as a white straight male it's the easiest for him to grasp.)
My issue is, and will always be, his team's inability (or unwillingness) to set and manage expectations, to understand how to run a national campaign, and how to take a freaking loss once in a while. Because, again, it's always a failing on behalf of the people, never the campaign, Bernie or his team.
To them, he didn't do well in the South because it was conservative. Instead of being introspective and saying "Hey, if my message isn't appealing to this block, where can I find common ground or build support for my position?" they just blame the people.
In states that aren't conservative that Bernie lost (i.e .Massachusetts and New York) the answer was disenfranchisement and voter fraud.
In states where there wasn't a convienient excuse for Bernie losing (ie Iowa, Nevada and Missouri), then it wasn't a loss it was really a tie!
His team has done everything in their power to push the blame on everyone else. It's always fraud, DWS, the DNC, uninformed voters, etc.