Wolff has his memoirs on line, but so far I haven't found the most important part, the events inside Columbia in 1968...
Somebody: The problem is we don't know if a society can actually be productively run this way. We do know that social democracy is somewhat sustainable and that centrally managed socialism works for a few decades. Even in the best scenarios, like in Catalonia during the Spanish Civil War, we're talking about brief historical interludes.
Revolutionary fervor inevitably dies down. Unless the system put into place can function well during times of political apathy and lack of popular engagement, it's just not going to replace capitalism.