<p>To provide a slightly different perspective: As a matter of fact, I have seen users with automatically generated names provide valuable content, answering questions and (as far as I can tell, not being a statistician myself) demonstrating real expertise.</p>

<p>So that's a direct answer to your question: Even if you are concerned about reciprocity and effort (and not merely about creating quality content) and unconvinced by appeals to general notions of the role of identity in scholarly discourse (yes, that's a fancy description of the PhD comic in @steffen answer!) the fact remains that anonymous users are productive members of this community. As a group, userXXX are perhaps a little more likely to ask an ill-conceived question and run (they are not the only ones to do that…) and nobody with such a name has reached stardom but they are not only “leechers” or randomly typing monkeys.</p>
