There is a strong emphasis on MO in favor of placing no impediments to an anonymous question by the next Fields Medalist. This has been tested in a number of ways. The down side is that anyone can make up a number theory question that cannot be resolved with current knowledge. When someone places such a question and refuses to give background, I generally believe that it is because they do not know any background, and vote to close. However, MO has some very, very strong mathematicians who regularly comment on questions without evident background, GH is one, Noam Elkies another.
After @Gerry's comment here, there is also no impediment to someone posting a disguised version of a known open problem and hoping to crowdsource it. That's what was discussed in this thread: http://tea.mathoverflow.net/discussion/1187/extending-from-a-plane-in-r3-again-and-again-and-again
Another example, both amusing and obnoxious, https://mathoverflow.net/questions/29534/the-product-of-n-radii-in-an-ellipse
The behavior of this person posting on both sites, with no detail, is a strong indication that the problem has no intrinsic value. One of the lessons of graduate school is, after all, how to write mathematics so that others can tell what you are getting at. Many people know this as undergraduates or earlier. In comparison, every time someone posts on MSE Main "My friend said that" I just cringe.