One of the reasons why we don’t focus on high school students is because often at that level, students, parents, and schools are focused on AP tests.
The problem with AP tests is that it promotes a kind of “arrival fallacy," which is the belief that when you arrive at a certain destination (passing the AP test), you'll be happy (and a proficient coder).
Ironically, in the process, the joy of CS is sacrificed for the sake of efficiently learning what you need to know for the test.
At the end of the day, we still recommend students take the class if it’s offered at their school, get a test prep book, and take it. It’s a signaling mechanism that is useful since we still live in an education system that prioritizes test scores.
I took every AP offered at my school. When I cleaned out my room, my years after graduating from college, my shelves were full of Barron's AP test prep books.
And I think it probably helped me get into Stanford. But it definitely didn't help prepare me for life.
Photo via Flickr User MarcieCasas