In our daily work we all make mistakes in our git commits. Sometimes this errors can easily be repaired just by reverting our commits. But if we are working in a public repository and we have accidentally pushed some sensitive information, we now have a problem.
That sensitive information is in our repository history and anybody who has the enough time to explore can gain access to that. Our clients or even ourselves are now dealing with a privacy issue.
We can always try to repair that commit in our local environment and push our code again using the --force parameter. But we know, when you do that, a kitten dies. And if your team members already pushed something, everything in the repository will be messed up.