1) It reinforces the idea that for young women, the only way to achieve business success is to be performatively "girly" -- being unceasingly cheerful and social, presenting a breathless aw-shucks ("so amazing!") demeanor, working on things like fashion lines and skin care products or on image-first careers like "Instagram influencer." Society accepts that ambitious young men will present to the world in lots of different ways, but when it comes to ambitious young women we try to hammer them all into the same shape.
2) It puts pressure on its readers, who are in an age bracket we generally associate with childhood, to trade the traditional privileges of childhood -- shielding from the pitiless demands of the market, space to experiment with different facets of their personality, time to dedicate to education and self-development -- for the precarious, rat-race lifestyle that adults live every day. Kids who are saying "there is no such thing as a regular 9 to 5. We work 24/7!" are kids who have internalized the idea that work is all there is, that their lives don't have room for anything else. That would be a sad thing for a fully grown adult to believe, much less a thirteen-year-old.