Socialism is not a system. It is a symptom present in many kinds of economic structures. Even capitalism in the U.S. harbors many forms of socialism, albeit private-sector oligarchically instead of public-sector controlled.
But to elevate the discussion to cause, the danger with these kinds of questions about economic terms we use so frequently is that their meaning is non-uniform and are often in the eye of the beholder, and endless debates ensue, as a result, merely emphasizing the unique interpretation of meaning rather than improving the efficiency of systems we ought to design.
So, before we can agree on the effectiveness of an economic system, we must first define its meaning plus a uniform definition of the principles under which that system operates. Today, all of our religions of economics are hanging by a dangerous thread on principles that are up for wild and free interpretation.
A reason why we need to reinvent economics.