It's not an important point because it doesn't affect the crux of his post but I feel the need to argue because you've clearly grossly misunderstood the meaning of a sentence that's easily understood by most.

He's not saying they can't be or shouldn't be judged on anything else. He's saying that, in practice, the person they're reporting to judges their work solely based on how it looks.

It doesn't matter whether or not this is true anyway. It's just a made up example to illustrate the idea.