I wrote about the purpose of self-improvement from a Marxist standpoint, primarily in response to the book that was advertised, that book being explicitly Marxist-Leninist. The applicability of Marx is self-evident. I wrote a separate reply comment, so maybe the relevance wasn’t that clear, that’s my bad in that case.

Besides the book, the meme is about communication between comrades. It is not a Christian “turn the other cheek” message that says kindness is in itself a virtue no matter who and where. Marx was excellent at polemic, and in my opinion it was constructive that he offered many useful refutations of common vulgar-socialist ideas, let alone bourgeois vulgar economy.

In general I don’t think it is true that Marx tore down comrades over nothing. I think you are repeating a meme about a perceived pettiness, for example in his attacks on Proudhon. But firstly Proudhon was not a comrade, secondly his ideas absolutely had to be dismantled, both for the working class and for Marx’s own theoretical clarification.