What if they learn without doing the worksheets?

Over at the new blog "Robin's Blue Skies", there is a wonderful post about how kids learn in the real world vs. workbook learning. I know people who are "school at home types" and I know that some of them think the idea of not having the kids sit down to do their school work for several hours every day seems crazy. However, if my son knows how to read, does it matter that he never struggled with "learning phonemic awareness"? If he never does a unit study in his life, but becomes an expert on prehistoric life just because it's what he spent time learning about on his own, does that make him less well educated? Quite often before having my kids sit down to do some sort of school work, I try to remember to ask myself, "is this actually what he needs to do in order to learn something? Is this a skill or knowledge he's going to acquire whether he does this or not? How often does he actually need to be doing this to master it?" I've learned to put it away unless it's actually something that they aren't going to get another way.
A few years ago a friend called to complain about her 6 year old's homework. The school had sent a worksheet designed to help the kids figure out how to choose books which are likely to have information you want about a specific topic. Aside from the fact that this is one of those things you learn by doing, normally without much thought, the worksheet was unnecessarily confusing. There was a list of titles and list of subjects which the child was supposed to match up. All of the titles and subjects were about clothing and costumes. I doubt if I could have matched up titles and subjects to their satisfaction because the meaning of the subjects was so vague and the titles so similar. So now something which should have been completely natural is presented to a child as a difficult skill they may not be able to master!
I think that a lot of what we make our kids do is like that. There are thousands of lesson plans, curriculum, worksheets, unit studies and what not out there to teach our kids things which they would have to be walking around with their eyes closed bumping into walls while plugging their ears not to learn in the normal course of life.
I'm not saying there's never a place for formal study in the life of a child. However, especially for younger kids, I think that most of what people do to teach kids is done for the benefit and comfort of the parent rather than because it is needed for the child to learn. Of course, we have been so indoctrinated to equate school work with actually becoming educated that it's amazing any of us questions this at all. And the fact of the matter is that the style we use to teach our children must be one we as parents can live with. I would hope that a mother who is forcing her children to do things which only lead to rebellion, frustration and thwart learning will in time seek another way. However, a mother who is profoundly uncomfortable with unschooling, but attempts it anyways is unlikely to be successful either. But, that's one of the advantages of homeschooling - there's no one way we must do things.