For instance this post
seems quite popular. I'd love to know the answer, does this mean it's just too hard?
First of all, it needs to be noted that most highly upvoted questions in this sub do actually get an answer within 9 hours of being posted as one of us analyzed. Additionally in the linked post, which also analyzed how many questions do get answer and which has been sadly deleted along with the account of the responsible moderator who left us for a variety of reasons, it became clear that highly upvoted questions receive an answer in 90% of all cases, slightly less upvoted questions are answered in over 75% of all cases, and questions receiving little to no upvotes are answered in over 50% of all cases. In light of the fact of the volume of questions we receive daily, this is a pretty good quota.
Now, as for questions that do not get an answer, this can have several reasons:
As our census results show, the make-up of our audience aligns pretty neatly with the general audience of reddit, meaning it is overwhelmingly male, white, straight, and from the US or another Western country as well as interested in Western European History, Military History, Medieval History, History of Ancient Greece/Rome and Science and Technology History.
Since our contributor base, flaired and unflaired, is recruited heavily from our general audience, this also represents the fields where we are strongest and the overwhelming perspectives of our contributors. This in turn means, that certain sub fields of historical study are not very well represented here.
Going by the list of currently flaired users and their expertise, we have 8 people dealing with African history, 14 people doing Middle Eastern History, 3 for the history of Ocenania, 3 people who across all regions specialize specifically in gender history, and one person with a special interest in Indian history.
This, of course, leads to the fact that when the occasional question concerning one of these fields turns up, there is a good chance there simply is no one here with the expertise to answer it.
The way in which a general public often approaches historical subjects and the way historical study approaches them does not necessarily align in all cases. The questions posed by a historical study are often influenced beforehand by what sources we know are available. Often times, within the course of a historical inquiry, a historian will restructure and adjust their question because what they originally set forth to do is not possible with the sources available.
Take, for example, this question if Sokrates even lifted. While it did get an answer by /u/iphikrates, this is in essence a question a trained historian would not ask. First, because of the limited source material on Sokrates' life, secondly because its pursuit would reveal little of interest within the realm of historic, academic study. While a historian would write about the views on physical fitness in ancient Greece in order to learn more about their society and their view of the world, the rather isolated question if Sokrates lifted is not one that is considered useful in an academic sense.
One the one hand, questions such as this are one of the great features of this sub: It allows people to explore the past simply because of genuine curiosity, not tied to the demands and culture of academic history, which I think is wonderful. On the other hand, it leads to questions that sometimes simply cannot be answered because of the lack of source material and study in the area. I mean take this question about the lyrics to a song of the punk band Crass: While its possible to answer part of the question, just exactly why Crass chose to write "10 million" instead of six will most likely forever remain a mystery unless you track one of them down and ask it.
This kind of difference between academic history and an approach based on this genuine kind of "showerthought" curiosity, that can be so wonderful, can also make it hard to answer questions.
What we provide here is an essence a platform for free education. All our moderators and contributors contribute and moderate voluntarily, their only compensation being that people will read their stuff and in the best case scenario give them meaningless internet points for it.
Also, answering questions here can be a lot of work. When it is not exactly your expertise researching, synthesizing, and writing an answer can take anywhere from one to several hours; a temporal luxury virtually none of us possesses all day, every day. Somebody might have the answer to a question but get distracted by life commitments, intending to return later but forgetting about. Or not see a question they could answer at all because they are otherwise engaged with university, writing a thesis, working their job, hanging out with their partner and so on and so forth.
Between e.g. all the contributors we have here specializing in the history of Nazi Germany and the Holocaust, we could probably answer over 90% of all questions posed concerning this subject but we can't do so because we do other stuff in our lives, stuff we often get paid to do and thus have a certain commitment to do them (sometimes unfortunately). So, it is the unlucky reality that some questions will remain unanswered, not because they are too hard or because there are no sources but because people who could answer them often don't have the time. And while, at least in my case, I find that always regrettable and want to take more time to write more answers, it sometimes simply is just not possible.
It could be that it's too hard to answer, or that nobody who reads the subreddit knows the answer. This is certainly an issue with a few questions. However, there are also other things that can cause a question to not get replies. For example, the person who knows enough to write an answer might not have time to do so. There have been quite a few questions I've seen that I would like to answer, but haven't been able to find time to due to work or social commitments (or sleep). People aren't on this subreddit 24/7, and when you only have comparatively few experts and when it can take an hour or two to write a good answer, questions are going to end up unanswered. Similarly, the person who knows the answer might not have seen the question. I tend to look at new questions, and I believe most other flaired users do. If a question is asked while I'm asleep, even if it's highly upvoted, I can and do miss it.
Sometimes, like with this question, the answer is just vastly complex. Asking what an entire group of people thought at a certain point in history is filled with all the sociological issues at the time, morality of different social classes, and so many other competing factors (like the difference between what is written about in historical references and how it may or may not have accurately reflected the real activities or beliefs of people at that time) that questions like that become even more difficult.
I get occasionaly questions like that, questions like "what would Bach have thought of Tchaikovsky's music" or "why wasn't Rock music written in the 1600s", which, while they may seem simple, require an extensive explanation of the entire progression of western musical theory and evolution of chord structures, the social and cultural norms of societies over centuries, as well as regional differences in taste, and how they shifted over space and time. And for a question that is not particularly relevant or really well thought out, sometimes it's just not worth the time and effort.
Yet another issue to consider is the availability of sources. For me, questions about everyday twentieth-century clothing can be very difficult to answer well. Twentieth century fashion studies tends to concentrate heavily on designers or very specific social groups; "where $populartrend came from" is usually addressed by bad popular books and articles, and since primary sources are not yet in the public domain, they're not a viable source the way 19th and 18th century portraits are. Other questions might require something like diaries and letters from a segment of the population that didn't tend to leave them.
Some flairs are very good at turning a question to make it more answerable with the available sources. I'm not one of them, unfortunately.