I will concede that high exposure to many different children will give someone a perspective that parents without the same experience wouldn't necessarily have. But none of those people you mention have an eighteen year obligation to rear the child. With a short term situation,
it's easier to just quit and let someone else take care of any problems.
I bet combat veterans, cancer survivors, etc will say that "you won't understand until you've experienced it" too. I can't imagine any list of activities that would allow me to truly understand what it's like to be black in today's America. So yeah, to be under that eighteen year obligation for a real flesh and blood child -- the one you actually got, not the one you imagined you might get -- also gives unique perspectives.
Sure it does. I'm sure that having to raise one's non-biological child (which would put you squarely in "you don't know what it's like because you didn't birth a child" territory) is also a bit of a struggle, no? It is, once again, a total cop-out to say someone can't discuss the subject because they are not included in the group most directly impacted by it. To use your analogy, yes, I've heard a lot of people say "you don't know what it's like to be black!" Of course I don't. Many of the things involved in those discussions, though, also applied to people who don't speak English well (go back to where you came from!), are brown-skinned-but-not-black, are female, have an obvious disability, etc.. There is common ground that allows people to talk about things. Likewise, no, someone might not know what it's like to have cancer... but they might have been there all through the last months, seen the effects, watched a loved one fade away... and that would certainly qualify them to join the discussion.
My mother likes to say she has helped raised a thousand kids, and she is right in a sense. She taught early childhood and was in charge of class after class of toddlers and 3-5 year olds for roughly 20 years. She saw kids all along the spectrum. She saw kids who were gender confused (already), and she dealt with having to "teach" children who did not speak five words of English... and parents who spoke less than that. She has heard "he started it" more than any one person should ever have to. She has seen kids playing doctor, boys offering to pee on a frog to comfort a screeching little girl, no shortage of impoverished children stealing lunches, and so on.
I'd like to think that, even if my sister and I did not exist, that sort of person would know quite a lot about the subject of spanking.
Also, to the point of your post, please remember that the people in question are not those who've raised a child to 18. A lot of the people offering opinions have children who seem to only just be reaching "that age," so other than the early period with the diapers and the saying cute things, it appears they are on even footing with not having experience with 6+ year olds
