I too am tired of the general ninja/rockstar terminology. To me though, this is different. It's referring to the aesthetic of their self-contained competition. To me, it's like playing a video game in which you are a space marine, which is already a thoroughly explored concept. It's just a framework on which to apply the particular mechanics of this site. For instance, they are saying things like "code wars ninja", not "Rails ninja". To me, that's different. To you, maybe not.