Pass through the Further? Isn't it just for tortured/impure souls Elise?

So why are children allowed there? children have no guile and are innocent, they have pure souls.

This makes no sense, maybe someone can elaborate? I am an Insidious fan for the most part, but this it getting to me. also, i didn't realize how they could toggle back and forth from the "good" place to the further, like Elise has done in this movie. This is one thing that doesn't make sense.

-"Pick a pet for the rugrat Bitch." -Freddy Krueger