Here is the question: morally, can such a practice improve a person? Can they become better people in the absence of interactions with other people?
It would seem to me that for a true Leftist, the answer would necessarily be no. They do not think in individual terms. They might have something to say about the economic position of the monastery, the selfishness of such a practice, the uselessness of such a practice and the like, but one person cannot become better for them EXCEPT in relation to others, and specifically as a member of one group in relation to another.
This is the root problem of Leftism: it is not a morality worthy of the name. Abusive abstraction inheres in it and cannot be removed by any means. It is an abuse of thought. It treats words like “society” and “class” as if they actually existed. Individuals exist-because they have bodies and names–but societies do not, not in the sense they intend.
Obviously, believing in God makes moral development a much more obvious thing: it consists in doing those things which bring you into closer communion with God.
But even absent a belief in God, I would argue that moral development consists in psychological development, which itself is at root learning to physically relax the body, learning to avoid spasms of learning and ratiocination, and learning to connect deeply with the social brain, and thus with other people. Having done that, all other virtues fall into line naturally.
I want to argue that Kum Nye is a moral system par excellence, even though it says NOTHING about morality at all.
Here is another way to put it: the more force needed for you to do the right thing, the less moral you are. In the worst cases, law alone and the threat of punishment keep you in line. Slightly better, your conscience and sense of guilt. Best, though, is consistently WANTING to be compassionate, generous, light-hearted, diligent, and honest. True morality is its own reward. It needs no justification, and no commentary by pundits.
Edit: I almost forgot an important point. I also want to argue that Leftism is the method emotionally dissociated individuals use to create the feeling of connecting to other people, through the medium of “society”. It can and does obviously induce strong passions, but not strong passions for actually helping people, not in the fully developed disease form we see in true Communists and Fascists (actually, Fascists are not as sick, because they at least do care about some people). No: it provokes strong connection to the IDEA of helping people, not the people themselves.
It thus constitutes a psychological trick to avoid unwanted emotions by pretending that they are already there, that virtue is already there, that moral coherence is already there, that they can both be good people and never, ever deal with their own unprocessed emotional shit.
I will note as well that this basic process could easily be applied to all dogmatisms, such as sick Christianity. God did not ask the Spaniards to torture Jews or Aztecs. No: sick people used religion as a means to justify their sickness in their own eyes.