Because Bernie was not a Democrat...he’s always identified himself as a socialist....the DNC should have stopped him in 2015 from getting on primary ballots.
But I think that they needed people to be ‘thrilled’ in the primary season and figured that he’d get more people to come out and vote....to engage. They just didn’t expect him to take 40-percent of the primary votes.
So now, they are stuck with a large part of the Democratic base (mostly young and in college), who think that Bernie led them to a better path ahead. Unless they do some creative work over the next two years, I think the Bernie effect will reoccur...creating more division within the party, and guaranteeing a 2020 loss.
I would even go and suggest in 2024...that a major party is created with 10-million Bernie-type voters, and taking a large chunk out of the Democratic base.
Could we see a replay of the 1824 election, where the voting went to the House?
One might even say a Shining Path, of for the illegal alien voters a Sendero Luminoso...
“the DNC should have stopped him in 2015 from getting on primary ballots.”
The party has no control over who runs in a primary under their banner. If I recall, the former head of the KKK, David Duke, ran as a Republican. Republicans were not amused. The only control the party has is who gets to use the party machinery and financing. Thus, incumbent Diane Feinstein, who was one of the two primary winners in California, was not endorsed by the party. Instead the party threw its support behind a candidate who ran, also as a Democrat, but far to Feinstein’s left. (In California, the two top vote-getters in the primary go on to face each other in the general election.)
The fact that Hillary was able to sew up the party machinery before she became the candidate is unusual and, probably, criminal. The criminal part comes in where the state parties simply transferred something like $84M dollars to her, which the individuals contributing it could not give directly due to the law. So, the party was used as a shell to transfer illegal payments. This will probably never see a court as she’s a Clinton...silly rabbit.)