As Lonelydragon has stated, it’s up to a parent to either take the ball and go with it, teaching their child at home, or just abandoned their child’s education and do nothing.
Social skills are social skills, unless children are locked in their house 24/7. Socializing comes natural with children. It’s up to a parent to make sure their home-schooled child is kept up to date with the latest social skills, when out in the public. I will agree that there is experience like one on one contact with other children.
I have know several parents(good parents), that have homeschooled their children and have been equal or better than public school or private school teachings.
The outcome all depends on the parents and what they are willing to give to their children, at home.