Hundreds of years ago people believed that some people around them were making bad things happen to them (giving them boils, making their crops fail and so on), and branded these people witches and had them burned at the stake or banished. It was a convenient (if dangerous) way to get rid of someone unpopular.
In the late 20th century political correctness served the same purpose. People could be eliminated from some environments by accusing them of sexual harassment or discrimination.