I've worked with many people like you, and I can say from experience that they are never as competent as they think they are. Often they are quite competent, and yet somehow they still overestimate their own skills and make life harder for everybody.
The type of person in question can be understood as somebody who equates technical skill with "not needing help." It's implicit in your post. Your mythical rock stars are extremely talented individuals, while what sets the incompetent apart is apparently their need for assurance from others.
The most competent software engineers (which I referred to as rock stars) don't know how to do everything. It can appear that way to someone unfamiliar with software. The best have a keen self-awareness of their abilities. They understand how much time it would take them to figure something out, and their likely success rate. When they give good estimates and have accurate confidence in their abilities, they create predictability for others around them. That makes them a net sink for stress.
Professional competence is literally the set of the things you can do without needing help. That doesn't mean you never ask for help. It just means there is an expectation that you can accomplish some things on your own. If you need help with everything forever, then you are fundamentally not useful and not coachable (which is worse). When needing help is anticipated and transient, that's a non-event. When your job is mostly things that you are expected to do yourself, but you need help with all of them, that creates stress for your peers and subordinates.
Indeed. Completely absent from the calculus are those who are glaringly ignorant as to their lack of knowledge or skill yet nevertheless supremely confident, and unchecked, will happily blaze a trail of carnage as far as they can travel.
It's a fine line, between blind, numbing incompetence and blind, bulldozing skill, and it's probably best to make sure youre never too close to either.
The type of person in question can be understood as somebody who equates technical skill with "not needing help." It's implicit in your post. Your mythical rock stars are extremely talented individuals, while what sets the incompetent apart is apparently their need for assurance from others.