This is a perceptive analysis. I have a few points that are more like alternative subpoints rather than arguments against your hypothesis.

1. The Biden comeback was almost like a Hollywood movie (a la Rocky). It’s tempting to speculate that the machinery painted Biden as down and out early on in order to orchestrate his arc after South Carolina (and remember that South Carolina was depicted as Sanders’ Waterloo in 2016).
2. In hindsight, Buttigieg seems more like a shadow candidate — a foil to garner media attention as the long shot likely to upset the apple cart (taking the focus away from Sanders’ status as the upset candidate). That Buttigieg gained a tiny lead so quickly and then lost it just as quickly (and endorsed Biden in a flash) suggests that his candidacy was part of the Biden comeback story.
3. The first step in knocking Sanders out of the race may have been to disable Warren. If she had remained a strong progressive candidate, she might have replaced Sanders if the party succeeded in eliminating him with all that Socialist and unelectability nonsense, and she would have been even stronger, combining her supporters with Sanders’ base. The first step in disabling Warren was to paint her as betraying progressives with her revision of the Medicare for All timetable. Revising a plan when it doesn’t seem to be working came natural to a planner like Warren, but the party-fueled media depicted the change as a retrenchment, and Sanders supporters acceded to the negative arc (the “you lied to me” off-microphone remark now seems more like a media fabrication than an actual rift as well). One analysis I read suggested that Wall Streeters actually viewed Warren as more of a threat than Sanders because she was more familiar with how the system worked and was more likely to succeed in disrupting the .1 percenters than Sanders would have been. So she had to be jettisoned first.
4. Relentless media attention on the so-called Bernie Bros. Say no more.
5. The entire Democratic Debate structure, like some sort of American Idol contest, was orchestrated to provide lots of distractions so that the candidate with the best name recognition (obviously Biden) would have the best chance to emerge as a front-runner. Biden fared poorly in debate reviews, but all he had to do was keep his nose above water, which he managed to do.
6. Over on the Republican side, Trump was actually more of a party favorite than the rest of the slate in 2016. Not the GOP, but the party of the wealthiest puppet masters (like the Kochs, who had previously engineered the Tea Party to push the Republican establishment more in their direction). In hindsight, it’s unlikely that any of Trump’s challengers would have disassembled government in favor of the vulture capitalists to the same extent that he did. Chaos and gridlock are much more amenable to the .1% than any sort of party hegemony. The vultures seem to have sacrificed their ideals of free trade to get Trump elected, but you’ll notice that Trump is slowly moving in their direction after blustering about NAFTA. Probably no Republican other than Trump could have gotten away with concessions to the wealthy as thoroughly as Trump has.