When Kevin is all grown up and has a kid of his own do you think he would intentionally leave him home alone to test and instill a sense of responsibility, survival, craftiness, and maturity in him recognizing the values of his situation as a kid?
Doubtful. The world we live in today is far different than the one Kevin survived in the early 90s.
Example: Kevin had to go to the grocery store. Should Kevin's child be in such a situation, he could go on the internet and in a couple of clicks have groceries delivered over night.