You're not criticising it? Come on, you are always criticising Catherine for something. What does "drawing by numbers" mean if not criticism? Saying anything is done "by numbers" is being derogatory about it. The Cambridge dictionary on line says:
done according to a plan that has been decided previously, without using your own imagination and ideas: This is painting by numbers - there's nothing original here.
All schools do teach drawing. It's part of the national curriculum for years 7 and 8. In year 9 if you opt to take art, and if you take Art GCSE from year 10, you can take the Fine Art option that hone those drawing skills, as they are one of the key skills for the topic. So, in effect, all artists who learned their skills in school are learning "by numbers", if you follow your logic.
Don't you think an "amazing art department" (I wouldn't know, I'll take your word on that), is more likely to encourage the opposite of drawing "by numbers", because it has the time and resources to encourage creativity and artistic freedom?
Why do you think loads of other people being able to do just as good a drawing devalues this one?