I often hear them being called rockstars too. Kind of unnecessary if you ask me. For instance if it comes to web accessibility I can destroy 9 out of 10 "rockstars", possibly more. They on the other hand might wipe the floor with me in advanced React concepts. I also think that a 10x engineer is only then truly 10x if they care very little or not at all about that "title". I have a friend whom I consider to be a 10x. Incredibly good engineer, and will jump on anything and everything, but also has the humility to listen to others and teach with kindness whenever necessary. Had he not had those qualities I wouldn't have given a flying fudge about his coding skills.