It makes the case that extrinsic motivations like reward systems harm intrinsic motivation, the natural desire to learn.
That's certainly been my experience. For example I think of all the books people hated reading because they were forced to in high school. I've read many of those books on my own and really appreciated them. Or all the people who got into tech because they loved it but ended up burning out and leaving the field because doing it for money slowly leached the joy out, leaving them only pain and resentment.
And it happens in the short term, too. If people are doing something for an intrinsic reward, those who just want the reward are going to do the absolute minimal job of it. Or just lie entirely. So reward systems that in theory are training kids to do good work instead can train them to slack off or become good liars.
I'm not saying don't do it. But I am saying that if you do, you should make very sure you're not harming children and child-parent relationships in the process.