Although an excess of actual home-schooling is probably part of the problem.
((Somehow, this took most of two hours to write. Must have been the check of C.C. and the wiki-rabbithole that took my time up. In reply to LordBaal, immediately ninjaed by Nenjin and then others.))
(Not that it is automatically bad, but it helps concentrate quiverfull and/or hippy-like parental 'indoctrination', and means no exposure to even the existence of less absolute stances, etc. Which is probably the intention in many cases, to greater or lesser disbenefit to those so effected. I think there are probably very good examples, too, but my impression is that it amplifies disfunctionality where it exists. Even more so than secularism in which school to attend, which was always more the problem (for some) around me where I grew up.)
A good population-wide guidance that is measured and flexible can prevent hot-spots of reactionism. Though often will create reactions in their own right. c.f. the failings/perceived-failings of Common Core. Or, more relevent the right (or not) to withhold sex. ed./whatever according to parents' requests (and, if not, that this leads to being removed from school or switched to one with more matching ideals).
This is, of course, squaring the circle. Some parents will not do a good job (or even talk honestly), and its for their sake that the establishment should be able to do what is right. Not that all tutors are guaranteed to be not as bad at it. Indeed, this is what the parents undoubtedly think, and thus the civil pressure against it... but in various cases this might even be objectively true. It is more that by dint of not being in isolation, the rougher edges should be discovered and countered earlier through more open discussion.
Either that or the much afeared-about societal-indoctrination will ride roughshod over the will of every decent parent! Welcoming in the Liberal(/Conservative) Hellscape Future, everybody! Who needs any schooling for anything? If your pa can't teach you all you need to know about everything (rabbit-skinning: food preparation and clothesmaking in one handy lesson...) then you can learn and teach your kids in twenty ten years' time...