I think “Rock Star” or “Ninja” or similar are actually rather harmless. On software engineering teams there can be wide disparities in skills/productivity. This disparity often only rears its ugly head on the job and not apparent during a job interview. This is a BIG problem. Amazingly, there can be a 10x even 100x productivity difference between team members. Again, impossible to pickup at interview time. These terms are signals to applicants. Your game better be tight or don’t bother applying.
“Rock Star” indicate a vibe, a pace, an energy. Even a bit reckless. Probably a result of the maleness of the field. In the heat of a deadline crunch this energy — backed by the ability to write code at pace that does not “break the build” — can be vital.