I wanted to add a perspective from someone who comes from a European country (Portugal) and have been living in the California for the past 4 and half years. Forgive me for the generalizations but one thing that I admire about Americans (at least Californians) is the strong positive "can-do" attitude to life. A fire that gets people to start their own businesses and think of new opportunities. It is obviously hard to pint-point the origin of any cultural trait but I believe that it also stems from the positive re-enforcement that this article is talking about. Along with most people of my generation that I know of, I was brought up with exactly the sort of message that this teacher is conveying ("you're not special"). I really think this contributes to the fact that Portuguese are one of the most risk averse people in the world. Even when we start our own businesses we pick very safe jobs (http://mvalente.eu/2011/03/08/the-paradox-of-portuguese-entr...)
I realize that it might be exaggerated positive re-enforcement in the US and that this can have very serious negative consequences. Learning to fail and balancing your future expectations is a requirement for good mental health. Just keep in mind that there are certainly good things about this attitude.
The positive encouragement model of raising/educating children is a relatively new thing in the US, so I don't think it has much to do with the "can-do" mentality. I'm in my mid-30s and we certainly didn't have it in school when I was growing up. I can remember my brother getting held back a grade.
If anything, I think its the current model that threatens the "can-do" attitude of the US, since I think a lot of the "can-do" attitude is really resilience. It an attitude that says "this won't be easy and I might fail, but I can always get up and try again".
If kids gets nothing but positive reinforcement, those initial failures are going to be particularly painful and discouraging. I think parents can teach their children so much by letting them fail (within boundaries) and giving them not self-confidence that they can do anything, but the self-confidence that they can handle any hardship. That's an important difference.
Before I start getting downvoted, I just want to say I haven't start yelling at kids to "get off my lawn!!" yet. :P
You can cultivate a positive "can-do" attitude without going overboard with positive reinforcement. A can-do attitude is easy to have if you are actually ready for anything.
I realize that it might be exaggerated positive re-enforcement in the US and that this can have very serious negative consequences. Learning to fail and balancing your future expectations is a requirement for good mental health. Just keep in mind that there are certainly good things about this attitude.