I mostly agree with you. But I also know there is a blurry line there. For example, I did some stupid stuff as a kid and it is a good things parents were there to intervene. I would not call their concern for my risk taking in that instance to be arrogant today.
But that is my perception of my individual upbringing. I have no real knowledge how parenting looks 'on average'. I know I was lucky in some ways; unlucky in others.
This is where it gets complicated, because the advice we get for parenting is a generic advice for a typically specific issue.
I am writing this as an expecting parent so take my musings as just that.
Yes, it is part of it, absolutely. But in the early years there's more to it that that.
When a four year old wants to eat ice cream all day and nothing else, are you asserting that they know better?
> I don't see the evidence that most parents know what's best for their child
That's not my assertion, my assertion is that it's their job, not that they're always good at it.