Karl Marx once wrote “communism is the solution of the riddle of history, and it knows itself to be this solution.”  And communism is the satisfying resolution of fiction that nearly all pop culture points at, but has to swerve away from.
There’s a common trope in media where it’s revealed, somewhere around the end of the story, that trying too hard to do good makes you evil. Game of Thrones, HBO’s Watchmen, the Hunger Games… their endings seem to come out of nowhere, as if they’re imposed from outside rather than obeying the story’s inner logic.
Any pop culture artifact is compelling to the extent that it taps into our real desire for change, justice, virtue, freedom, resolution, etc. But it can never go all the way down this road, it can’t consummate this desire, because that would be too threatening to the reigning social order. John Stuart Mill, father of enlightened liberalism and one of the early advocates of free speech, explicitly warned against extending this freedom to socialists:
An opinion that corn dealers are starvers of the poor, or that private property is robbery, ought to be unmolested when simply circulated through the press, but may justly incur punishment when delivered orally to an excited mob assembled before the house of a corn dealer, or when handed about among the same mob in the form of a placard. 
Why do stories that start out so promising and suggestive founder towards the very end? Because any consistent working-out of problems tends towards communism. Such a consistent working-out has to be sabotaged, thwarted; to do that, the principle of consistency itself has to be chucked overboard. Killmonger, Daenerys Targaryen, Alma Coin, and Lady Trieu all break bad sort of inexplicably, punishing the viewer for supporting the power-claim of someone with good politics. The message is unequivocal: “Having good politics doesn’t make you fit to rule! Having no politics does!”
These stories cynically wring emotional identification out of the viewer by giving them a taste of communism, and then when it no longer needs that emotional buy-in — because the show’s wrapping up — they insult the viewer for falling for it to begin with. Whereas Wandering Earth may reward an audience rooting for all of humanity collaborating to save Earth, Christian Thorne points out Inglourious Basterds “gets us to share those fantasies [of killing Hitler] and then it starts calling the fantasies into question. … [Tarantino] hates us for liking his movies the way we do; he hates us because he can so easily bring us round to enjoying the sight of people being gathered into a closed space so that they can be exterminated.”  But Thorne is wrong to see this as a peculiar quirk of Tarantino’s: hating your audience is endemic to mass media.
This dynamic is just a more specific case of the general form of liberal wisdom. Namely: the truth is always whatever conclusion you reach after you get over your youthful radicalism. This gesture is as obligatory and reflexive as making the sign of the cross when you walk into a church. We ostentatiously signal maturity and seriousness by condemning radicalism. No matter what interesting ideas we start out with (and there really are a whole lot of interesting ideas in my estimation), we always have to end on a note of fidelity to the status quo. And this distorts the whole story, especially towards its end.
The swerve, capitalism’s yanking the football away at the last second, is comically predictable. It goes far beyond media: Capitalism is the stale prank that can’t stop repeating itself, worming its way into the substance of everyday life, making it ever stupider and more self-defeating (what Marx termed real subsumption). But we shouldn’t blame each other for still making a run for Lucy’s football — like religion, mass media is both an expression of and a protest against real suffering. We may fall for the trick, but our steps get a little bit faster every time.
Who are showrunners accountable to at the end of a successful franchise? Certainly not the viewers, whose semi-conscious revolutionary desires fueled the thing’s success. They are accountable only to future investors, who need to be reassured that the showrunners are a good investment. The showrunners thus find themselves obliged to engage in performative treachery as a way of virtue signaling to the market. As Black Sails and Marx’s Inferno have adequately shown, treachery is the founding sin of capitalism, and all major productions have to ritualistically reenact this gesture if they’re ever going to find their way into the big leagues. John Stuart Mill via Long John Silver: “I made arrangements to ensure that when we leave here, it is with compromises in place that will diffuse any threat of widespread rebellion.” 
“Curse your sudden but inevitable betrayal!” Yes. But don’t turn cynical; let yourself imagine what real follow-through would look like.
Marx, Karl 1974, Early Writings, Harmondsworth: Penguin. ↩
Robert Levine and Jonathan E. Steinberg, Black Sails. 04x10 — XXXVIII. ↩