As I understand it and I might be wrong (I hope I am wrong!) There some sickos in our midst (Misnagdim and Chasidim alike) who follow the shita that biah (intercourse) with a person who is less than 9 years is not considered a biah (some authorities say the limit is 3 years and one day ). So they believe they can do whatever they want with a person as long as he or she are less than 9 years and one day
My father who is a wise man, always came home from work less than one hour before shabbos and he never let me go to the mikvah by myself.
The Monsey Tzadik