I don't understand what is wrong with 'cults' and 'hippies' as long as they don't violate the rights of their children they should be left alone in freedom.
Keeping them out of public schools isn't violating the rights of their children, in fact, it probably protects them to a degree.
Theodore Roosevelt was homschooled and is arguably one of the brightest, most well read presidents in teh United States - although unfortunately he wasn't so conservative...
Basically nothing. I think it's better for children going to school and having contact not only with other childs but also adults who aren't all friends of the parents. I wrote some of my reasons before but am too lazy now to elaborate much more. :)
So was William Buckley until he went to high school.