This analysis by @DavidOAtkins is very good. The failure of Bernie to win doesn't show that a progressive candidate/agenda can't win, it shows that you can't win a Democratic primary by running against the party https://washingtonmonthly.com/2020/04/11/leftist-policy-didnt-lose-marxist-electoral-theory-did/

The fact that the factional strategy even looked like it had a *chance* to work is solely an artifact of an anachronistic primary calendar front-loaded with states with few African-American voters. If we started with South Carolina and Michigan Bernie never would have led.

Or, at least, would not have led using the same approach. If South Carolina was before Iowa, it seems unlikely that he would have delegated the SC operation to a Stein '16 voter with no serious connection to the state. Another reason to get rid of the ridiculous primary calendar.

It's also worth noting that even if you DID succeed in grinding out a nomination with a third of the vote and little African-American support, the nomination would be a poisoned chalice that would probably result in a failed presidency, but that's another thread.

One other point. The model behind this doomed strategy seems to be Trump '16, but was Trump actually a factional candidate? Is there any evidence he would have lost a national ranked choice vote or a head-to-head with Jeb! or Rubio?

The idea that Trump was factional basically represents both Republican elites and a lot of the media being in denial over the obvious fact that racism is a lot more popular among Republican voters than...literally any orthodox economic policy being offered by the party.