Capitalism opens an avenue for greed to be used for the benefit of the many, whereas any other form of resource distribution has no place for greed and as such no place for the greedy. At that point it becomes the same kind of discussion as the prohibition discussion. Do you ban it or do you allow and regulate it. Banning greed won’t make it go away, it will only force it into hiding and to undermine the current system. Capitalism forces greed to the surface, at which point people can have a discussion about how much greed should be permitted.