Bosses love to think that they know it all, but they operate on limited info like everybody else. This just shows how stupid it is to work hard for a job, when everything is based on impressions and not on any kind of objective measures.
It’s a running joke where I work just how hard it is to get fired. One of the few stories I know of someone who was fired involved an employee for whom my employer paid multiple times for courses of rehab. He was finally fired when after all that they found him at his desk so drunk they basically couldn’t wake him at all.
On my first job, there were several employees whose jobs was to aimlessly wander around the office because they had a problem with their logins when they were hired and nobody bothered to fix it for them. Companies really don’t give a shit.