It's not home schooling that is the problem here, it's people like Casey Parsons who should never have had children to start with. Unfortunately there is no way to monitor people and decide whether they will be good parents or not, until after the fact. I believe Erica would have been abused no matter where she ended up going to school.
I also think that the family should bear some blame as well, since they seemed to be aware that things were not right and did nothing about it. We all bear a responsibility to report abuse when we see it, especially if it's family. Casey bears the majority of the blame, but she is not the only one who allowed this to go on.
My point is, there are many kids who are and were home schooled and some of them have gone on to have successful lives. For every case you see like this one, there are hundreds more that turn out just fine. I agree that every state should have a monitoring system and it should be carried out regularly, but the entire system of home schooling is not to blame.... only the ones who abuse the system.