In high school? I assume this means US high school (I just skimmed the article) and I would agree with its conclusions. High school is where society should be raising its baseline level of competence. The things you learn in high school are, for the most part, things which society has deemed important and which will be of benefit to you as a member of society and not just in a professional sense. You're swimming against the tide if you get too choosy then. It's fine to do more, but high school is a terrible time in life to start deciding "this subject is unimportant based on what I think I want to do later." You may very well be prematurely closing doors you want to go through later.
tl;dr - do as well as you can at everything in high school. Start getting choosy in college.