Argh I had a several-paragraph answer typed up, and my computer crashed.

Anyway, what I was going to say is that an AMA is probably higher up the reliability scale than historical texts that are invaluable, such as Josephus. So it could totally be of use to a historian. However, historical texts are never accepted unthinkingly, at least not by good historians. Logical leaps, faulty information, and bias are all important to examine in any historical text--they would be for using reddit comments, too.

Moreover, part of the reason part texts that are potentially less reliable are so important is that in many cases, they're all we've got. To historians, a murky Josephus that we have to interrogate for bias and unreliability is far better than no Josephus at all (perish the thought!). If, in some horrible future time, reddit archives compose a large proportion of what we know about what is now the present (shudder), historians would likely use reddit as a way of filling in gaps. But in all likelihood, we'll leave behind loads of archival materials that will survive better than reddit comments, making more reputable records the preference for future historians.

So in the case of the Holocaust, there are loads of more thorough and more widely circulated 1st hand accounts, so a future-historian needing to resort to reddit is a bit unlikely. But for something niche, like a former WBC member, could totally be best preserved in reddit. Or things that are more mundane, that don't have a book written about them sitting in every library. Like, what was life like for a typical computer repairman? While this is of somewhat limited use on its own for much the same reasons that we don't allow anecdotes here, when combined with other evidence about society in general it could be used to fill in a gap in future people's knowledge of how computers were used and abused in the early 21st century.

Unless you are writing about Reddit demographics probably not.

In History, Anthropology, and Sociology there is something called an Institutional Review Board (IRB). They come from the medical fields where the purpose is to prevent a researcher from acting unethically towards subjects (lying to them, hurting them, etc). In the social sciences the idea is the same, to prevent the researcher from overly pressuring the subject, incriminating themselves, etc... They are also meant to protect the researcher by preventing them from breaking local laws, pushing people to far, etc...

A researcher files a research plan with their University IRB which reviews their intended methodology and questions. If they need revisions the plan is marked so and sent back. They are a big deal on sociology where studies of large groups of people to create statistics are common.

Reddit, by its design, offers no protections for either researcher or subject except anonymity. Anyplace where IRBs are required, sociology, anthropology, some history offices, would likely dismiss any research without it. You could get your interview, but getting it published might be very hard.

EDIT: pressuring not presuming.

I think you are talking about AMA's. I would say an AMA would be interesting so long as it is a verified AMA. You can always message the user to offer further proof or even for an email/phone number to conduct a phone interview. If it is the Westboro Baptist interview do keep in mind who the AMA was (the grandson of the cult leader) and any biases etc.

That said it depends on the topic. For a sociology class I used a users story that reinforced a point on the use of mice in labs.