I'm terrible at drawing. My son asked me the other day to draw some animals for him on a piece of paper and thank God he's a toddler and is easily impressed otherwise he'd be laughing at my utter lack of any artistic skill.
Sure, I was able to get the semblance of an elephant, a lion, and a giraffe for him down on paper, but anything beyond basic shapes is way out of my league. In my defense, however, you could look at what I drew and still identify that it was an animal.
But when it comes to professional artists, like, let's say, someone who's contracted by the police to sketch up potential suspects, you'd want someone with technical acumen.