This is unfortunately all too true. I have relatives that like to think they're exempt from society (witnesses) and pushed that onto their kids, those kids are almost 18 and cannot carry out basic conversations. They are socially about 12 or less. They will never be able to leave home nor persue their own interests.

Home schooling works better when kids have at least had elementary schooling. High school I would argue is where things break down a lot, and for some students there isn't a social experience outside of constant bullying and stress over things that don't matter.