People are on the Internet to communicate, play, do business, etc. To do whatever they like, basically. And it's their right to do that as anonymously as they want. But anonymity isn't all or nothing. One can compartmentalize ones online activity. Sure, use Facebook and other social media with family and friends. But don't say much that could feed stylometric analysis. Have other personas for sensitive online activity. And practice good OPSEC, to prevent them from becoming associated with ones real name.