Family History is history. I would guess that if you took a poll among all of the members of The Church of Jesus Christ of Latter-day Saints, you would find that the subject of history was about as popular with members as with the general population. The number of postsecondary degrees conferred in the United States in the area of Humanities has remained fairly constant over the past thirty or so years. See the Institute of Education Sciences, National Center for Education Statistics, Bachelor's, master's, and doctor's degrees conferred by postsecondary institutions, by field of study: Selected years, 1970-71 through 2011-12. What is significant is that degrees in the humanities hover around 16 to 17%. Other than a course or two in high school (if that) few people have much of a background in history.
In addition, most historians focus on the facts of history, while genealogists focus on discovering historical sources. In my experience, few genealogists, even those with a background in history, could tell you what was happening in Europe at the time their ancestors left their country or origin. It is the rare family historian that can relate the movement of their ancestors from say, Virginia, to Kentucky and tell you what was going on in history of the country at the time.
However, general history awareness is not the overriding limiting factor in family history research. What is really at the core of the limits to extending family lines, even among those who reach a expert level of research is the fact that there are limits to the availability and even the existence of historical documents.
Let me illustrate my conclusion with a hypothetical situation comparing two researchers. In the first situation we have Researcher Doe who is a "history buff" and in fact, has an advanced degree in U.S. history. The second family historian is Researcher Roe who has been doing family history for many years but has no particular interest in history, as such. Both of these researchers are looking for an ancestor in the same part of the United States at the same time. In fact, they find that they have a common ancestor. They have both been researching this common ancestor for many years and without any knowledge of the other's research, they have both learned that the common ancestor was abandoned as an infant on the steps of the local church. Despite the years of research and the extensive backgrounds of both these researchers, finding the ancestor's parents have proved to be impossible.
My point here is simple. There are practical limits to family history. Those limits are not set by the amount of specialized knowledge of the researchers, but by the availability of historical source records containing information about individuals and families. It is inevitable that every single one of my ancestral lines will end at the point where records cease to be available. Even though this is an undeniable fact, the reality is that very few family historians ever reach that point. In other words, few family histories are limited by the unavailability of records, they are limited more by the lack of knowledge and motivation of the researchers.
It is further my own experience that most researchers stop long before the sources have been exhausted. This is where a lack of historical context begins to become more and more important as factor in this lack of progress. The most common problem I find is the inability to trace the ancestral line beyond an immigrant. In nearly every case, this occurs at a time when the researcher is not even aware of the identity of the country or origin. For example, many researchers are looking for an ancestor who came from Germany in the 1800s, without a shred of information about where in Europe the person originated or whether or not the person even spoke German. If this reference to "Germany" makes no sense to you, then you need to study a few historical maps of Europe and the boundary changes that occurred to see what I am referring to.
So, what should be our reaction to an elusive ancestor? We need to dig in and discover the history and then realistically evaluate whether or not sources are actually available.