I mean Bernie's particular and specific narrative toward "the establishment" certainly at times teetered on corrosive IMO. But that is only because I think that simple narrative in general is corrosive.
Though I am not sure I am going to judge him for that when self-perceived noble lies or simple narratives are present in almost any political campaign and will likely remain so indefinitely. And they certainly were around with Hillary and Obama. So it comes off a bit hypocritical to shame Bernie for them. Since it has been a long-standing tool to sway a largely uninformed, identity focused and emotionally driven electorate on either side that prefers simple narratives over the realities of necessary complexity and nuance.
Bernie certainly did play up the establishment as a pejorative simple narrative at times. Which I do think has been a fairly cancerous cultural narrative for our democracy and inadvertently makes getting to the congressional reforms Bernie spoke about, harder. Because it sets up this all or nothing dynamic that is not how our system works, which sets up inevitable disappointment and creates a negative feedback loop of apathy and cynicism.
But Bernie didn't start this trend. The whole "both sides," hyper-partisanship, incrementalism=corruption, and the "they just care about money and propping up their pet industries" has been building up for some time on both sides. It was heavy in liberal political comedy in the 90's and 2000's. And the crazy inverted version on right-wing talk radio. The internet loves providing echo chambers for them and cable news thrives on aspects of it.
Hilary was not ever prepared in the primary or general to effectively counter that establishment narrative though... Or to at least find a message that could get through the noise to offset that disadvantage or subvert it. That is also setting aside the structural failings of her campaign that Bernie had nothing to do with.
