This works also great in startups where nobody really knows what he is doing and no one has firm grasp on what people produce/should produce except impressions. Knowing who really produces requires good management that has time to look at the details. That requires stability, non panic mode and sane politics.

Overworked manager will take overconfident person over humble cautious one, because the illusion feels good.

Those overconfident people rarely do nothing and are completely incapable. That is strawman situation, basically. Oftentimes they eventually succeed, altrough it takes more time, is overall somewhat less effective, their code is harder to maintain or something of that sort.