Oh and in terms of unschoolers, guiding kids to research topics they interested in, taking them to the library, playing board games, exploring nature, showing them practical examples in maths eg cooking, shopping etc - they are all great things but they are things that an engaged parent would do anyway. It is however no substitute for school and a good education.
I cannot see for the life of me how a child who spent their childhood being unschooled would ever gain the critical thinking and analysis skills to even attempt an arts degree. Any sort of maths picked up along the way may be adequate to deduce the best value item when shopping but would fall short of the type of maths needed to attempt any sort of STEM degree at uni.
Even if they don't want to go to uni and want a practical hands on job eg mechanic, a good education sets kids up for success in every day life.
At best, it is setting the kids up for a difficult time in adulthood attempting to catch up to their peers and function adequately in society. At worst I believe it is setting them up for failure.