I'm glad that doctors have very specific criteria for ADHD. But I also feel that the criteria should be more strict because almost every other child seems to suffer from some sort of attention disorder these days. Either it is being diagnosed too quickly or somewhere, somehow, we as parents and teachers, are doing something wrong.
Like the article said, children naturally have short attention spans. It gets better as children grow and our attention span is best when we are adults. Some people though are born with slightly shorter attention spans that more or less stay the same throughout life. I think it's a genetic thing.
Looking at the increase in ADD and ADHD diagnoses however, I think there is something else going on that is cause attention problems in children. Perhaps too much stimuli since birth in the form of TV, video games, cell phones, etc? I think it's possible. Too much stimuli has a negative affect on attentiveness.