Do we really need school? I don't mean education, just...

Do we really need school? I don't mean education, just forced schooling: six classes a day, five days a week, nine months a year, for twelve years. Is this deadly routine really necessary? And if so, for what? Don't hide behind reading, writing, and arithmetic as a rationale, because 2 million happy homeschoolers have surely put that banal justification to rest.