The goal that most parents have for their child if you were to ask them is for them to be successful in life. No matter what level of success a parent has experienced in their own life i'm sure that most people if you ask them would say that they would like their child to go beyond what they have achieved.
The dilema for most is how to have the kind of effect on a child to help them to reach the heights of success.
For some people they feel that the best way to help a child to reach their potential is to push them as hard as possible. This is usually done by pointing out how much better they could have done at something, even on occassions when they have done quite well at a particular thing.
The belief that goes along with this is that if a child receives liberal amounts of constructive criticism it will inspire them to go beyond their usual abilities and out do themselves. While in some cases parents have seen that their child has responded to this favourably and has indeed gone on to push themsleves to higher levels of achievement, other cases can be cited where children have been negatively impacted by this