I think the biggest, more important issue I had with homeschooling than socialization, or parents who don't know how to educate... was exposure to different races, cultures, etc. Research, and learning about culture, is not the same as seeing culture day to day. There was a girl who did homeschooling through the school, she would get the work, do it at home, and then once a month she'd attend a day of school to hand in all her work. She was REALLY SMART, but she was sheltered, and had major problems with understanding and accepting other cultures, races, etc.
Parents really do need to have the ability to go on "vacation," to other countries in order to teach culture, or at least go to the city... I grew up in the suburbs and country, but my parents are both English, and both love India. I spent much of my childhood in Little India in Toronto, but also in England... I experienced different cultures first hand, I was raised on Punjabi music, and curries, and my bestfriend was from Pakistani immigrants to England... I wasn't homeschooled, and I'm glad I wasnt, but I would have liked much better to have gone to an English Boarding School, and I would have LOVED to have attended a Welsh Boarding School... as my dads family is Welsh, and I resent my parents a bit for not ensuring I grew up speaking Welsh as well as English.