Uhm, I have to admit I'd never noticed that. While I agree with Stephen's answer, I'm guessing that text is from way back when the site first got started and we had a lower volume of questions. Personally, I'm leaning towards removing that suggestion and making the text read:
If you're not sure if your question is on-topic, ask on meta.
I don't see much benefit in urging people to post things that may be off topic. I'll take upvotes to this answer as meaning people agree that the text should be modified.
