This one seems reasonable to me; it's a blog or mailing list discussion topic, not really a specific mathematics question. Although phrased as a question, it's

This one seems reasonable to me; it's a blog or mailing list discussion topic, not really a specific mathematics question. Although phrased as a question, it's obviously a rhetorical one; what the asker really means is, "I would like to start a discussion in which everyone lists their favorite examples of surprising mathematics results". It's a fine discussion to have, but StackOverflow wants their site to be about actual questions, not "what's your favorite X" type discussions, which seems like a legitimate preference.