Praise is often conditional. Praise focuses on the end result. The struggle, the falling down, the mistakes, the hard work leading up to the achievement are not acknowledged nearly as much. Praise is often inaccurate. Praise that is not descriptive of what the child is actually doing can convey to children that we're really not paying close attention.
Praise emphasizes external validation over internal feelings of satisfaction.
Children who have grown accustomed to praise can lose touch with the inherent feelings of accomplishment that come with their achievements. To this day, I want outside acknowledgment for every task, no matter how trivial. Praise can lead to competition. When children are taught to rely on external validation for their accomplishments, they often become competitive with siblings and peers, in an attempt to win more of the recognition. This perspective on praise can be difficult to hear.