AskHistorians

You joke, but ruling with an iron fist in an academic sub is preferable. Requiring a bit of academic integrity in responses to questions is what makes a history sub valid. For instance, requiring all responses to provide sources should be a bare minimum.

Shit man, even AskHistorians on R*ddit doesn't require sources in the original answer. From the Old Place:

We do not require sources to be preemptively listed in an answer on /r/AskHistorians, but do expect that respondents be familiar with relevant and reliable literature on the topic, and that answers reflect current academic understanding or debates on the subject at hand.

Even though sources are not mandatory, if someone asks you to provide sources in good faith, please provide them willingly and happily. If you are not prepared to substantiate your claims when asked, please think twice before answering. Requests for sources which are not fulfilled within a reasonable span of time will generally result in the removal of the answer.