Great post. I try to only post photos of my children where you can't see their faces. Recently I posted a photo of my daughter playing tball but you could only see her back. I do have one pic on social media where you can see my daughter's face but she is wearing a hat and sunglasses so it is mostly covered.
Besides the whole Big Brother thing you bring up and not wanting to leave a massive digital trail of my kids, I also don't want to invade their privacy and post pictures of them they may not like having been posted when they get older. I would imagine most people won't want an entire chronicling of their youth plastered all over the internet.