In the literal translation, whistleblowers are people who blow their whistles and thus point out grievances. Without such indications, offenses such as money laundering, corruption, discrimination, wage dumping or tax evasion would often not be detected. And that would be fatal, because such actions are not only against the law, they also contradict our social values.
And although the topic is so important to society, whistleblowers have often needed a lot of courage in the past, because they sometimes had to reckon with considerable negative consequences. This is not the only reason why there are now laws that protect whistleblowers.