a candidate is better off if they haven't had to get through a grueling primary.
Among other things, Hartmann kept referring to her as a "centrist Democrat," and that was false. She wasn't a Democratic Socialist like Bernie. She was a progressive or liberal Democrat.
There are real centrist Democrats, like Joe Manchin and John Federman, and she wasn't one of them. But people who didn't know any better bought the idea that she wasn't any more liberal than Manchin, and concluded there wasn't any point to vote.
Thom Hartmann, 2016: "And then there's the question of who is more electable in a general election: an unabashedly progressive democrat, like Bernie Sanders; or a "centrist" democrat, like Hillary Clinton." https://www.thomhartmann.com/blog/2016/02/if-you-want-win-go-progressive
Because of Bernie's choice, echoed by Thom Hartmann, to repeatedly label her a centrist, Hillary had to defend her record of being a progressive. Of course that didn't help her in the general. She was being attacked from both sides: as a centrist from Bernie's side, and as a "communist liberal" from the other. Instead of being able to move to the center -- as is normal in a general election campaign -- she had to shore up her support from Bernie supporters, thanks in part to people like Thom Hartmann..
"Hillary Clinton Is A Progressive Democrat, Despite What You May Have Heard."
"If Sanders is the standard by which youre going to decide whether a politician is a progressive, then almost nobody from the Democratic Party would qualify. Take Sanders out of the equation, and suddenly Clinton looks an awful lot like a mainstream progressive -- firmly on the left side of the American ideological spectrum and maybe on the left side of the Democratic Partys, as well."
"One reason its easy to miss this is that Clintons domestic policy agenda doesnt include one signature idea or position thats going to dominate the headlines or get activists excited. Instead, its a series of proposals that, together, would fortify the social safety net, strengthen regulation of industry, and bolster public services. To the extent these programs require new spending, the money would largely come from new taxes on the wealthy."
https://www.huffpost.com/entry/hillary-clinton-progressive_n_572cca08e4b0bc9cb0469098