"Common sense" what a phrase.
It's always used by people in positions of authority. It means "Don't you dare question me about what I just told you." Parents and politicians love this phrase. It's hard to argue with.
A lot of incompetance, ignorance, and laziness, is at the core of this declaration.
First, just because a great deal of people believe something does not mean they are right. For a brief period in history, common sense said that tomatoes were poisonous.
Second, expecting someone to blindly accept whatever you say, that expectation can only be met by using force, or the threat of force. Even then, it's difficult to achieve. People don't always show what they are thinking.
Third, making a claim that one does not understand enough to explain it has the potential to undermine credibility. Since people in authority like to be credible, the constant use of this phrase is puzzling.