Also, we HN commenters typically see the success stories around us at work, not the failure stories. We all know that guy on the QA team who's a genius and credits his success to homeschooling, but we don't know the countless numbers of grown adults who are trapped as housewives who can't get a job because they never learned 5th grade multiplication.
Sometimes you don't have to dig. A ton of moms in my wife's church group permanently pulled their kids out of public school in recent years, and they will openly admit that it's about keeping their kids away from "those" people, where the definition of "those" runs the gamut.
The overwhelming majority of other homeschooling parents they had contact with also held separatist motivations.