Yes, thank you for being understanding. I think it's better to avoid calling people brainwashed because -- as one liberal in this thread pointed out -- it denies agency which our interlocutors plainly do have which makes them much more responsible for their bad epistemology than the theory of "brainwashing" allows for.
If we want to persuade people -- and I've seen that you have incredible enthusiasm for that cause! -- we must do our best to meet them where they actually are rather than where we imagine them to be.
I'll get off my soapbox here, I just wanted to mention it. I wish you all the best in your efforts!
I suppose it's just a matter of syntax, but I first read this as a very silly statement wherein "communism" is an offshoot of "Marxism / Leninism".
Anyway, don't worry, I'm familiar with the "real Marxism has never been tried!" line that some people have for various reasons, but I a) can't see how this is particularly useful as a distinction compared to other states and b) don't think this remotely answers my question.
I think you and I both know why the so-called marxists who say "real Marxism has never been tried" exist, or at least our beliefs on the matter are a close enough parallel that it's not a very enticing discussion, but what you have failed to do is explain the basic prompt of why a westerner would support a state like China.
I can give an internally-consistent answer for these groups and yourself coming to their beliefs: You all live to varying degrees in a bubble of western Discourse and pseudo-historical mythmaking.
The "never been tried" Marxist believes everything the State Department says about its enemies but still believes in some sort of ever-failing communism like a good little Trot because they are, for the time being and in part motivated by their social position, appalled by what capitalism has wrought even in the imperial core and want something better even if they struggle to conceive what that could be in practical terms, since every success of socialism has been transmuted into an ultimate failure. Nonetheless, "there must be an alternative," and that possibility, however hazy, is worth fighting for over the corrupt establishment.
The liberal believes everything the State Department says about its enemies and comes to the reasonable conclusion (if we assume the State Department is honest) that socialism has failed its many chances and therefore "there is no alternative". They are more likely to have a higher social position than the previous group because it is much easier to say capitalism works when it works for you.
The "tankie" is typically the worst off of the three groups in social position, with long term prospects that look pretty grim, and this has pushed them into a desperation to find a way to improve their prospects since they can't afford a hazy future and communalist circle-jerking but the invisible hand of the free market would crush them even faster, so they do something that these other groups are not driven to, which is some level of serious research, and by this means they were able to accept that the State Department lies as often as it speaks and that they have been born into the slightly unnerving position of being nestled in the imperial core as the empire runs roughshod over as much of the world as it can. Whether they simply concluded that states like Russia or Iran were plainly the lesser of two evils for their opposition to NATO, or they found a more extreme position like genuinely believing in the project of Socialism with Chinese Characteristics, they were able to develop a framework that gives them a path forward where previously they felt they had none.
Of course, various biographical details can also be vitally important, like being the descendant of defectors vs generic diaspora, or knowing people who are. I'm white as the driven snow, but I know Chinese people from both groups. The "tankie" one didn't persuade me on very much (though I learned a lot about the Korean War and various elements of the 20th century PRC) but the diaspora descendant taught me things that I still am trying to process, because they made genuinely ridiculous claims (e.g. Mao burning down libraries during the Civil War) that I have not been able to find repeated by even the most ridiculous anti-PRC rag when I search online. There's a bizarre sort of cult to intergenerational trauma that seems to emerge where stories are embellished and exaggerated over time (deliberately or not) and the truth of these stories cannot be questioned because, in so many words, "it's their truth."
I meant it when I said I'm still processing it, because to me it's in many respects a bizarre behavior even though it's actually not that hard to explain sociologically (view it like religious trauma and it's trivially simple). I think there is more to learn from it, but I couldn't tell you what.