they are acting like Bernie is an insurgent who wants to destroy the party.
https://twitter.com/berniesanders/status/1231021453270769664
yeah this was a really dumb moment for Bernie. He could erase most of the ill will from things like this that by going all in with Biden/against Trump.
What are you asking here? They aren't philosophically close. The issue that Bernie holds most important they are miles apart on. Most progressives and his supporters feel like neo-liberalism is a poor alternative to conservatism, some feel even worse about it. Bernie and the progressives have absolutely nothing to gain by simply going in for Biden against trump. Why? That would render everything he's done useless. It isn't like we don't have history of this playing out already, he's not stupid. He moved aside for Hillary and did more events for her than she did for Obama, it got him and the progressives absolutely nothing. The platform didn't move left at the convention, no progressives got house or senate seats in '16, and the establishment democrats still blame him for Hillary losing.
I get the fear of another four years of Trump, that's what this song and dance is all about. Acting as if he has anything to gain by moving aside is dishonest. The Democrats made this bed, it isn't his job to clean it up for them, especially given he's an independent. Quid pro quo.