Area 51 is confusing to new users. Many of them try to ask example questions here on Discuss.Area51, presumably because they don't know the difference between an example question and a discuss question, or because they can't find the "propose an example question" box (it's well-hidden!), or something.
I think it would be good to add a custom close reason here that says something like "this question should be asked on a proposal page as an example question", with links to relevant FAQs and so forth. This would provide more guidance to users that find themselves in the wrong place than the existing blanket off-topic close reason, which is not very specific.