It seems to me that 43% support among Democrat primary voters is fairly broad, but I guess that's just a debate about semantics.

I would argue, however, that he faced tremendous opposition from the wealthy, and that translated into most corporate media either attacking him or ignoring him, so his supporters could only be heard on social media.

Look at the Michigan county-by-county primary results (better yet: compare 2020 to 2016) and tell me that Democratic Socialism is a viable position in the modern Democratic party. Sanders didn't even take Washtenaw this go-round. I think it's very likely that Sanders overperformance in 2016 was really an artifact for a lot of deep-seated dislike and distrust of Hillary Clinton (something Biden himself was reported sour about in the wake of the 2016 fiasco).

Corporate opposition is a just-so story. Until his campaign fell apart, Sanders stomped Biden in earned media coverage.

I would say Sanders is popular, and not just among "online people." He won Nevada, including a decisive victory among Hispanics. The state as a whole is a working class state, and Hispanics there especially so. While he's not more popular than Biden, but he represents the only other "lane" in the Democratic Party that has meaningful purchase with actual voters, especially "not online" voters. And of course, let's not forget that anti-Wall Street, anti-corporate sentiment is emergent on the right as well--especially among persuadable voters and independents.

What isn't popular among voters, by contrast, is the woke managerialism lane Warren has come to represent. That's significant both because it points to how the party should recalibrate its message, and also because of its implications for the party's management structure (where the woke managerialists have outsize power). I suspect Democrats' reshuffling of the primaries will significantly ameliorate both problems.

I may have gotten myself in trouble here implying that Sanders is unpopular; he's not. He's just not viable. You can't win the Democratic nomination without the Black vote, and, for whatever reason, Sanders just wasn't able to connect there. It's academic now, of course; Sanders isn't going to run again.

I'm not a Warren fan either. I'm the weirdo in this conversation who was actually rooting for Biden.

See my comment above.

Sanders fell apart among black voters in the south for a very good reason — he talked down to them as if he was the first person to think that talking to them about Socialism was a good idea, as if Paul Robeson or Bayard Rustin never existed. One of my (white) college classmates who was very heavily involved as a campaign worker for him told me, “Who are those people?” I said “Don’t look at me, it’s your campaign.”

That being said he was probably the only person who could’ve stopped the union workers in Ohio from flipping to Trump.