The most important learning step for children is interaction with others. If they are sitting in front of the screen all day, they do not learn to share, wait their turn, or even something as simples as manners. Children need to be in contact with other children, adults, and animals. They need to experience things first hand not off a computer screen. When children log on to the computer their innocence is noticeable.
Children are an easy target for adults who pose to be other children with similar interests.
Sexual offenders often chat online with children and then make plans to meet them or slowly filter information about them. Children are innocents and honesty on the computer can pose some huge problems. They do not know any better and usually it will only harm them in the end. One benefit of the computer age is that children are becoming smarter. They are growing up computer literate and will have that as a huge advantage.