Well, she is learning it now and I wouldn't call her "useless". But her level of experience and knowledge is far below "software engineer" and if she were a guy she couldn't get away with it.
Except, make 'technical management' decisions like "we should use mongodb because it's web-scale".
I think this is untrue. I know a lot of male "sofware engineers" who are totally incompetent and remain well employed.