…the state is the only human Gemeinschaft which lays claim to the monopoly on the legitimated use of physical force. However, this monopoly is limited to a certain geographical area, and in fact this limitation to a particular area is one of the things that defines a state. 
When I was a kid I also believed ‘communists should ditch that label, for PR reasons.’ Now I think we make more headway owning it than dishonestly disavowing it. Not least because someone will almost always bring up Stalin no matter what we call ourselves.
Stalin is a powerful trope. His name stands for the perverse emergence of injustice from the overzealous pursuit of justice. It’s dramatic irony, a morality tale about how power corrupts. That mythic trope stands as a barricade for socialism no matter what kind of spin you put on socialism.
The ritual denunciation of Stalin on “the left”:
- presents a utopia of socialism without antagonism,
- flatters first-worlders and academics,
- spares people the unpleasantness of interrogating how their ideas about the past were formed, and
- makes a virtue of losing and waiting.
First-worlders get to feel better about themselves if they believe that all the socialist revolutions that took place in the third world “weren’t really socialist.” The same goes for denigrating national liberation of ex-colonies as bourgeois/Bonapartist/etc. Intellectuals get to feel more important if they believe really existing socialism “failed” because of faulty ideas. This lends itself to an interpretation of history where ideas are the motive force, and fidelity to the text is paramount. It’s not surprising that they would also trash “developmentalism” as “merely” bringing food security, electricity, literacy, education, industry, healthcare, job security, etc.
What are the crimes normally attributed to Stalin? The show trials, the purges, the gulag, forced collectivization… in other words: state violence. The socialisms that define themselves in opposition to Stalin therefore downplay state violence as much as they can. This yields a socialism that’s just trying to sell itself to people like any other commodity. Disavowing negativity/terror means ignoring that the USSR made the world a better place partly by scaring porkie. 
The question of who’s doing violence to whom, and to what end, is the fundamental problem of politics. It’s capitalism’s answer to this question that makes us hate it so much. “Nobody does violence to anybody” sounds good, but it’s not actually a political position. Political positions require charting out a plausible course from where we are now into the glorious future ahead, and that path goes through socialist states. Statehood is (a monopoly on legitimate) violence. Thus, the demonization of Stalin is the demonization of socialist statehood itself.
In other words, pretending our new thing is sui generis and doesn’t have anything to do with “Stalinism” doesn’t actually mean we’ll face different problems, or have better solutions. Stalin faced problems that were generic to socialism. Socialism isn’t just an infinitely malleable brand in need of better marketing, it’s a class project with definite and durable contours. We don’t actually transcend these problems just by calling ourselves something else, just like we don’t transcend capitalism by calling ourselves post-capitalist.
Anticommunism is most efficiently compressed and transmitted as demonization of Stalin, and it stands in the way of Americans joining any possible global left wing project, since it prejudices them against left authority everywhere (but especially overseas). International solidarity requires that we abandon great power chauvinism. Hatred of Stalin reinforces great power chauvinism, therefore defending Stalin weakens it.
If we decline to draw from the entire history of socialism-in-power in favor of utopian socialism or pragmatic liberalism, the range of results we can obtain will be limited to those achieved by utopian socialism (evanescent communes) and pragmatic liberalism (hellworld).