May I wonder why this question is not welcomed: 

[accidental-unplanned-breakthroughs-in-mathematics](http://mathoverflow.net/questions/152476/accidental-unplanned-breakthroughs-in-mathematics/152477#152477)

see the votes-down. And unfriendly responses.

but many others are even more broad or more opinion-based are welcomed in MO?

[your-favorite-surprising-connections-in-mathematics](http://mathoverflow.net/questions/14574/your-favorite-surprising-connections-in-mathematics?rq=1)

[what-are-some-slogans-that-express-mathematical-tricks?](http://mathoverflow.net/questions/8874/what-are-some-slogans-that-express-mathematical-tricks?rq=1)

[what-are-some-mathematical-sculptures?](http://mathoverflow.net/questions/32479/what-are-some-mathematical-sculptures?rq=1)

see the votes-up.


Could the reason behind is an effect of a [broken window theory](http://zh.wikipedia.org/wiki/%E7%A0%B4%E7%AA%97%E6%95%88%E5%BA%94) or some sort of biased/discrimination against the post person? (Do people know the communities suppression may hurt a person esteem?) Is there some way to improve the question?

To me, this quesiont [accidental-unplanned-breakthroughs-in-mathematics](http://mathoverflow.net/questions/152476/accidental-unplanned-breakthroughs-in-mathematics/152477#152477) is more serious than the other threes. It is meant to be a good starting point to see how many commonly easily granted-taken math studies have some nontrivial twists behind. It is a serious question.