It's funny. You have created yourself a paradox. Replace comp sci with being a teacher. You have made the claim now that teachers can be incompetent but Johnny cannot be. Let's say Johnny wants to become a teacher and puts in lots of effort but just cannot teach. Now he is an incompetent teacher but at what point did he go from being judged on effort to being judged on ability? When he wanted to be a teacher and got a free pass for being a bad teacher? When he went for his first job and got a free pass for failing his exams? When his entire class learned nothing because he was unable to teach even though he put in lots of effort?

Where is the transition? At some point ability is more important than effort.