It's "the worst idea in the world" because it perpetuates the idea that certain words or thoughts are taboo.

This doesn't mean people stop having them.

This just means that they are labelled/judged if they have them.

Guess what happens then? People keep it to themselves. And then they vote for Trump. Why? Because, he is a ridiculous loudmouth who is very out of touch with most of reality. But, he doesn't feel the need to be censored. And to people who haven't spoken out due to fear of reprisal, this is an admiral characteristic. He gives them validation.

So yeah, political correctness is retarded.