Here's the part your missing: every person has an opinion. If someone posts an opinion that another person disagrees with, by nature, one is encouraged to respond and disagree with it. What you call criticism another one might also call discussion. This isn't a place to have hundreds of people talking to themselves. It's supposed to be about sharing opinions.
If an opinion is an overreaction and one another disagrees with, why shouldn't they express that? It seems you're looking for asylum from disagreement.