There are actually two types of home schoolers. One type home schools because they don't like what is being taught in the schools. The other type doesn't like the fact that the schools aren't teaching enough.<quoted text>
Religious home schoolers tend to do so because they don't want their children exposed to opposing ideas. They want to re-enforce their particular viewpoint and keep their children from really learning about the variety of ways of looking at the world.
In contrast, the non-religious home schoolers tend to do so because they don't like how watered down the curriculum has become over the years. In contrast to the religious type, the non-religious type wants the children to learn *more*, not less.
My ex-wife and I home schooled our daughter until she was ready for high school (when our daughter said she would prefer to go to the public school for the social aspects). By the time she was 12, my daughter was reading and understanding Plato and Shakespeare. She could write a well-reasoned research paper and asked for a book on reptile surgery for her 13th birthday. She has one more year of high school and hopes to become a veterinarian.
Not all home schoolers are poorly schooled. Most are, but not all. Much depends on the motivations and education of the parents.