Most (but not all) homeschoolers are notably devoted to the practice of religious faith; and faith provides a metastory, a framework, in which the virtues of marriage and family make sense. More religious devotion = more marriage. Less religious devotion = less marriage. It's not true in every case, but overall, it's a solid sociological fact.
And why do we WANT to have a marriage norm: more people married, and in strong, durable, function-rich marriages?
Because it's pleasing to God and good for people. It helps you become mature, wise, unselfish, healthy, and happy. And it produces the kind of children we think are delightful, the kind of teens we think are hopeful, the kind of people-on-the-street and people-in-the-neighborhood and people-at-the-workplace we rely on to be sane and stable. The bricks. And without marriage and family--- without the bricks --- societies collapse.
Vastly under-valued benefit of homeschooling.
Homeschooling can only work where two parents are very committed and capable. When you can't teach someone how to tie their shoes h.s. cannot work.