I disagree, I think school has a profound effect at an early age. Just like you experienced, but in a negative way, unfortunately. I'm happy you were able to turn it into a positive motivator instead of accepting the prognosis of obviously poor teachers.

My son is already reading at an advanced level and doing math while his classmates barely know the alphabet. He hates school because it's so boring. We are sending him to a class with similarly gifted children so that he won't hate school and will be challenged. Keeping him in a class where kids don't learn as quickly as he does would definitely be a disaster in this case.