I think its a tricky one. All kids, homeschooled ones included, are members of the society I live in and I do think its reasonable to take an interest in them. I am concerned about schools even though we are not currently using them. I am concerned with provision for SEN although none of my kids have additional needs. I campaigned to legalise same sex marriage although I am married to a different sex partner. I am concerned about prisons, even though I hope never to be using one
(no I am not equating schools with prisons).
Therefore I think its reasonable to be interested in why people are HEing, if it impacts on how their kids are brought up.
One reason that hasn't been mentioned for HEing, that does disproportionately apply to homeschoolers with larger families, is fundamentalist Christianity. The quiverfull movement, basically. No quiverfull is not as prevalent among homeschooling in the UK, but its not unknown. (and just to be clear, I am NOT saying that all large families or even all large Christian families are quiverfull).
I don't personally agree with the teachings of the quiverfull movement and I am uneasy about arguing for the rights of homeschoolers to perpetrate quiverfull ideas. For me, they conflict with other things which are too important to me. Teaching kids tolerance, teaching our girls that they are for more than raising kids and marrying. Teaching children that homosexuality is not wrong, that love is love.
I absolutely support homeschooling as an option for everyone and will defend it against criticism based on lack of knowledge. But that doesn't mean I will defend every homeschooler against any criticism whatsohever. I don't support people's right to teach their kids to hate others in society. I don't support people's right to teach their kids sexist ideas. That's about kids' rights to learn about their world. I don't believe personally that there is an easy solution to this. I am not saying that I would stop these people from homeschooling, for example.
But I will certainly, personally, speak out where I see it rather than supporting them because, like me, they are homeschoolers. I do NOT want to be conflated with fundamentalist right wingers, just because we have both made the same educational choices. I do not consider myself to have anything whatsohever in common with the Duggars, for example, aside from our choice of educational method.
Abuse happens in the homeschooling community. It happens everywhere. Personally, I think we'd be much better as a community if, rather than defensively shouting "No! No abuse here! How dare you!", rather listening to people's concerns, understanding where they come from, and having a dialogue.
(although I am with you on the subject of irritating gurus. There's at least two I can think of...)