I concede in the previous post that a sufficiently radical alteration of the human nature might make egalitarian capitalism work.
The incentives problem can under some very implausible assumptions be handled. I mean, look at me: I'm not getting paid for writing this blog, yet I do it anyway.
But egalitarian socialism will still be impossible because of the second socialist computation problem.
Cohen is both an egalitarian and socialist, but he is smart enough in this book to argue for equality without mentioning socialism, as well.