Students' contact with society is still relatively simple or only one-sided. If you don't participate, you have no right to comment It is unscientific to draw conclusions based on only one piece of news.
Secondly, listen to both clearly. Having said that, most people in China can't do it. Prisoners still have the right to defend themselves. To judge one thing, we must listen to the reasons of both sides. For example, criticizing the urban management, but I once heard a city manager say that most of the things on the street stalls are fake or not up to standard, and they pretend to be poor online if they have wages. Grass has grass and sheep has sheep.
Finally, it is a generalization problem. In other words, to say bad, people in a province are bad people. Henan people are all bad people, and so on.
Your teacher is typical and divorced from reality. Criticizing society is not a slogan, let alone digging the dark side of society, which makes people feel that our world is the worst, but to find our own social deficiencies, analyze them with rational thinking, and influence and change them through certain legal means.
What your teacher said is a slave, who can only shout slogans and can't analyze and think for himself.