This article is old, but a good read: https://www.vox.com/policy-and-politics/2017/11/14/16640082/donna-brazile-warren-bernie-sanders-democratic-primary-rigged

The 2016 Democratic primary wasn’t rigged by the DNC, and it certainly wasn’t rigged against Sanders. But Democratic elites did try to make Clinton’s nomination as inevitable, as preordained, as possible. And the party is still managing the resentment that engendered in voters. “Once somebody doesn’t trust you,” sighs Buckley, the New Hampshire Democratic chair, “it’s very hard to get that trust back.”

The DNC did mess with the 2016 preselections, but the article argues that that probably benefited Sanders, by giving him much more of a platform than he would otherwise have had.

But it also seems like a footgun for the democrats as a whole, and probably contributed to the 2016 anti-establishment vibe that led to the Trump win

You need to understand the mentality. If they like something, then everyone in the whole world must like it, too.

If people think it was the DNC all I'll say is "could be". The main stream media very much did Bernie dirty. If they reported on Bernie's campaign at all, it was to essentially mention that he was not a real candidate. They never reported on the massive rally turnouts he was having. If people consuming MSM saw how much energy was in the Bernie campaign I would bet that would have gotten more people interested in his message and to the primary to vote for him.