I was home schooled from a young age and I think the reason for it is that the child will not be put under pressure to do "worldly things" at school. My mom also thought public schools weren't good enough at teaching kids how to read and write. I think what happens is that these kids are in even more of a bubble than normal JW kids. As a kid I never really knew any kids that weren't JWs, so to me everything seemed perfectly normal. I imagine if I had gone to a regular school I may have been exposed to differing views and not gotten baptized at such a young age.
I must say though that I notice some people think a good education can't be attained through home schooling. This isn't the case there are many alternative schools were most of the work is done at home but teachers and tutors are available when needed. It also depends on how much time the parents devote to it. I went to an alternative school but was still able to go to a four year university. The real problem is you don't learn how to make any friends. Everybody you know is from this little small group of JW kids, those are your friends almost by default.