In the "Genealogy Department" of Just Answer, we have an education, in one form or another, that qualifies us as "experts". Most, if not all, of our research is done online. We know of websites you have never heard of, and we also have paid subscriptions to several websites. Many people may know where and what to search for but arriving at the correct answer lies in the analysis all of the available information.
To put it simply, just as a doctor uses his education and experience to arrive at a diagnosis, we use our education and experience to arrive at a logical deduction.