I like the intent of the quote, but not the conclusion. What is it that gives us value? I.e., from what is our self-worth derived? There are three possible answers as I see it, and perhaps some other answers as well which are, however, impossible (as in, we derive our value from god). So, one answer is that we are inherently valuable, we are valuable to ourselves, in and of ourselves. The problem with this answer is that from this perspective, others are only valuable to us insofar as they are useful to making ourselves feel better about ourselves. This is called egoism, or individualism, and it basically treats other people as means to an end. It is the route of selfishness, which says that what only matters to us is what happens to us, and what happens to other people doesn't concern us except so far as we ourselves are affected.
The second answer is the one Marx gives (which makes sense now that I think about it, being the central philosopher for communism). It states that we derive our values from meaningful relationships with other people, that our lives are only meaningful insofar as we are able to give of ourselves, to love others, to help others in an infinite cycle of reciprocation. The problem with this answer is just the conclusion he himself reaches, which is that we are utterly worthless in isolation of others. He rejects any form of individualism, so this perspective, while I am not sure it has a commonly known name, I call an extreme form of altruism. Where egoism is self-love and narcissism, altruism is other-love with a consequent nihilism about how one can love himself regardless of how others love him (or her!).
I find both of these answers to be lacking, for the obvious reason that both are true to an extent. If we follow Aristotle's lead, and try to find the happy medium, true virtue lies in finding value in both ourselves and others. Both of these answers are extremes; the real answer, i believe, lies in the vast middle ground between them. This perspective is what I call organicism. It sees people both as individual organisms in their own rights, and as belonging to ever-increasing spheres of organisms extending outwards, through family and friends, peers, communities, and outwards to nations, species, and even all living beings. Organismic love means to see another not as an "other", but as another part of one's self, as much as one identifies with the new organism which the organization of those previously-separate organisms creates. So I would disagree with Karl Marx here as vehemently as I would disagree with an Ayn Rand.