A Facebook speaker said to Techcrunch that they are giving this feature to the user to report any comment when it is "Offensive," "Misleading" and "Off Topic."
According to Facebook, we are not testing on dislike button, and we will never launch dislike button for users. Its create fear and insecurity among user to share anything. According to them, we are only providing a small and useful feature to users to make our community great and user-friendly.
According to use, this will be a handy feature for users, and it will create an excellent user-friendly environment for users.