May I wonder why this question is not welcomed:

accidental-unplanned-breakthroughs-in-mathematics

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

what-are-some-slogans-that-express-mathematical-tricks?

what-are-some-mathematical-sculptures?

see the votes-up.

Could the reason behind is an effect of a broken window theory 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 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.