I disagree that parents do not do childcare, but that's just an argument about semantics.
For what it's worth, I don't believe that I had any less "leverage" over my dd's upbringing than a sahp, because I was still the one making decisions about who would care for her, how she would be cared for etc. Just as the parents of older children make decisions about how to educate their children and so on. I appreciate that I was fortunate enough to be able to afford choices that wouldn't be open to everyone, but equally, as you've said, some sahps will be better equipped to nurture their dc at home than others. There will always be individual differences.
As it happens, I think the small amount of paid childcare that my dc did have was invaluable, in that it added an additional dimension that neither dh nor I could have offered. Our amazing nanny brought her own dd to our home with her, and her daughter became like an older sibling to my dd, who is an only child - I could never have replicated that relationship had I stayed at home. DD also benefited from learning the nanny's native language (which dh and I also speak by virtue of having lived in the nanny's country previously) and also from her wonderful musical and artistic talents - much greater than mine our dh's!
However, the nanny was only in our house for around four hours every morning. Typically, dd was often asleep for a couple of those hours, so it was only a very small part of her day, and the rest of the care was shared between dh and me, working opposite "shifts". That wasn't the way it had to be, but it was the way that we chose to arrange our lives at the time.
Our nanny wasn't a childcare professional, but the friend of a friend, chosen specifically because her values and beliefs about raising children were in accordance with our own. She developed an incredibly strong bond with our dd and still travels 200+ miles to visit her each year, more than 8 years after we moved away from where we were living. We also travel the other way, and they speak on Skype regularly. Is the bond between her and dd as strong as the bond between me and dd? No, of course it isn't, but I will remain eternally grateful for the fact that dd has such a close and trusting relationship with another adult who cares about her. Not to mention the bond that she has with the nanny's dd, which has surprised all of us by surviving a move half way across the country.
We haven't had to use paid childcare since moving all those years ago, as dh and I were both able to work flexibly enough to cover the school runs and holidays between us, with my parents stepping in as and when needed. She has a wonderful relationship with my mum and dad, and now chooses to go to their house a couple of days after school each week, even though dh could be at home if she didn't. (If dh wasn't home, would that count as childcare in your opinion, I wonder?)
It seems from your posts that you are trying to suggest that wohps are somehow less involved in "bringing up" their dc than sahps. I disagree.
You also seem to be suggesting that (unless a child's parents are what you describe as "poor role models"), children will be better off at home with a parent. I assume that's why you believe that there is "inherent virtue" in being at home with the children. Again, I disagree.
Some children will be better off with a parent, undoubtedly. Others will do just as well in a childcare setting. Some, like my dd, will benefit positively from what a high quality childcare arrangement has to offer. That isn't because I lack the linguistic or emotional skills to interact with my dd effectively. It is simply that children sometimes benefit from developing relationships with different people who are able to offer different things. I accept that it is also important for children in the early years to develop a secure attachment to their primary caregiver, but that doesn't mean that they have to be with that person 24/7.
Everybody's situation is different. It is bit possible to generalise.