I don't think that's a very good example. I would never tell someone how to perform an operation BECAUSE I am not a doctor. I could tell someone about
an operation in the most general of senses.
So, someone without a child could talk about child raising in a general sense, but not really have any ground to stand on in regards to the actual execution because they haven't actually got any experience.
I think it's worth noting that kids can be incredibly manipulative in regards to their parents emotions and can usually play them quite well. The parent is also going to be deeply emotionally invested in their child and might not always have the heart to punish every little infraction. I'm just saying that because I don't know how many people take into account that it is actually a person they will be dealing with and not one of those toys that claimed to learn the more you interact with it.
I'm not saying anyone is right or wrong, I mean, I've no kids either (thank god), so I'm in the same boat as most of us, I just don't pretend that there's some sort of perfect plan that will produce children that grow into good adults. Your kid could be psychologically predisposed to hate authority and being the sort of no-nonsense parent isn't going to be productive at all and will end up creating a rift in the relationship. The same could be said for a parent who tries to be their best friend when maybe their kid is the kind that needs a lot of guidance before they can cope on their own.