I noticed this section in the UX FAQ:
What makes a good question?
Prefer questions that elicit definitive answers or solutions rather than prolonged discussions. Remember, this a Q&A site, not a discussion board.
"Prefer questions..." sounds very awkward and unnatural, although it could be technically correct as in "You should prefer questions..." (a command to prefer questions).
I think it should be changed from "Prefer" to "We prefer", or even something a bit stronger like:
"[Please] only ask questions that elicit definitive answers...".