No purely socialist system has ever worked.

Things aren't so simple. Much depends on what you mean by 'worked', for example. I have spoken to a goodly number of Hungarians, Russians and so on who have quite independently made the point that for all the very real hardships under communist rule, they found the capitalist systems that arrived as they broke away much worse, especially for things like unemployment. Of course if you define 'working' to be doing what capitalist economies do, then it is tautalogical to say nothing else works as well.