https://www.vox.com/the-big-idea/2018/6/22/17490410/democratic-party-sanders-left-liberal-interparty-fights-sanders-socialism-clintonism

Good article. I think this is the heart of it:

«Why is it important to recognize that today’s progressive brawlers have a rich and fruitful historical legacy inside the Democratic Party? Because those activists’ tendency to view the party as a monolithically hostile, alien force carries with it a major downside, which was all too painfully manifested in 2016: Useful critique and insurgent energy can curdle into cynical disaffection.»