Snugs,
Actually, IMO, the real problem is just the opposite. Many homeschoolers are too involved in activities. We homeschool as do most of our friends. We have to make it a point to say no to great opportunities that arise for homeschool kids.
Last month, I joined a couple hundred homeschool kids and families for a day at the State Capital. All the kids were engaged and very well behaved. The socialization argument actually falls flat when you take a hard look at it. The discitnary definition reads "To make fit for compainonship with others." Definition "People aside from oneself." This implies that socialism is the ability to interact with those who are not just like you, ie' people ouotside your peer group. That is what most homeschool kids excel at.
To add to your story, I grew up in a neighborhood full of kids and went to a local school. I do not keep in touch with anyone form those days either. It has nothing to do with the volume of people. It has to do with my lack of desire to hang out with them.
I often think that fact that I had no brothers and sisters and the only children I spent time with out of school were not really of my choice gave me really no real desire to have children of my own or really be able to interact easily with children even to today. I have even done children outreach etc but often unless a child latches onto me find it difficult. Though I thorough enjoy and appreciate and love watching children and in my own way love them and wish I could interact more. My "friends" either were from church or my parents organised that children in our street visited or I went with them. We owned a shop and our cleaner lived in the same street so often they would arrange for me to go round with her and her children especially in the summer holidays. I feel this is factor in my interaction with children throughout my life.