I don't think there is a rule against it per say but just as a thought experiment, I don't think it would go down well. Perhaps a better question would be why is a Marxism society accepted?
Broadly, because Marxism isn't the same thing as Leninism and because non-Leninist Marxism, though it wanted more radical change, was a central source of ideas, organization, and activism in the movement from classical capitalism to the modern mixed economy throughout the developed world.
> it wanted more radical change, was a central source of ideas
You could say the same thing about Fascism
To attempt to dispense with either: Marxism very much was and Fascism very much was not an important source of ideas, activism, and organization driving the transition from relatively pure capitalism (“pure” in the sense of being essentially the dominant system in the developed West criticized under that name by Marx, not pure in the sense of embodying the post hoc idealistic rationalizations invented in response to criticism of that system) to the modern mixed economy.
They explicitly seek to align themselves with disadvantaged persons which arises sympathy in the part of the audience and therefore attracts activists. Fascism on the other hand does not have this sympathetic attraction as its authoritarian nature is comparatively undisguised.