You clearly have never seen a dog suffer from parvo. We had a pup die of parvo when I was a kid and the most horrible thing was not even watching him die, but to know that he was pretty much being eaten alive by this virus from the inside and was in horrible pain. If you are willing to risk this for the sake of some esoteric idea about "natural living", you obviously care more about your ideals than about your pup. But what's worse, you will put every little pup that crosses your path at risk. Just like unvaccinated kids (don't get me started!) pose a mortal risk to small babies.
I'm sorry, I somewhat understand where you are coming from and I agree we over-vaccinate and use way too much unnatural stuff in food and lots of things, but it's a knee jerk reaction. Not all things that are natural are good, not all things that are man-made are bad. It reminds me of a Tim Minchin song from his show with the Sydney Symphony Orchestra. I think it's called "The fence".