Being able to say what you think is an important human right BUT what you can say about other people is covered by rules.
These protect us all from unfair treatment by the press. You may never have appeared in a newspaper or been on TV, but if you did you'd want to be treated properly.
How would you feel if a TV presenter told people you had been rude to a shop assistant, when you hadn't?
You wouldn't like it and neither do celebrities, politicians and sports people. If they feel they have been treated unfairly they can try to get things put right in several ways.