One way is to reject all criticism and attack anyone who dares to try, hopefully preventing future criticism so that maybe, just maybe, your boss won't notice your incompetence.
Another is to accept the criticism, get better, and then not have to worry about your job because you do it well.
If someone isn't capable of actually doing their job, they can't really pick the second choice. In that case, it's in everyone else's best interest to expose the situation and stabilize the company, saving their own jobs.
One way is to reject all criticism and attack anyone who dares to try, hopefully preventing future criticism so that maybe, just maybe, your boss won't notice your incompetence.
Another is to accept the criticism, get better, and then not have to worry about your job because you do it well.
If someone isn't capable of actually doing their job, they can't really pick the second choice. In that case, it's in everyone else's best interest to expose the situation and stabilize the company, saving their own jobs.