My dad spanked me with his hand when I was a toddler. Not overly hard, and not after age 4, but still.
Do I think my dad could have made better parenting choices? Yes. Am I happy that he made substantial advances from what he learned as a kid? Also yes.
A small number of parents are legitimately abusive and should have their kids taken away. Some parents are amazing and talented care givers. Most are just muddling through and fall somewhere in between.
As a parent I am doing my best to keep raising the bar - no corporal punishment over here! But I am sure my children will still find myriad ways in which I have failed them as a parent. Kids don’t come with a manual, and “professional advice” is astoundingly inconsistent/conflicting. I think most parents are doing their best, it is just a hard and poorly understood problem.